hi!
add your raw.githubusercontent.com link to the end of the url:
https://rawgit.loltek.net/

example:
to get: https://raw.githubusercontent.com/loltek/rawgit.loltek.net/master/src/www/script.php 
go to:  https://rawgit.loltek.net/https://raw.githubusercontent.com/loltek/rawgit.loltek.net/master/src/www/script.php


github repo (bugs/development/blahblah): https://github.com/loltek/rawgit.loltek.net

source code for this script: 


<?php

declare(strict_types=1);
//die("PHP SCRIPT IS RUNNING");
// CLOUDATCOST FUCKED US OVER, HACKING TOGETER A DREAMHOST COMPATIBLE VERSION ASAP
function dd(...$args)
{
    $file = debug_backtrace()[0]['file'];
    $line = debug_backtrace()[0]['line'];
    echo "dd() called from $file:$line\n";
    var_dump(...$args);
    die();
}

error_reporting(E_ALL);
ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
set_error_handler(function ($errno, $errstr, $errfile, $errline, array $errcontext) {
    if (!(error_reporting() & $errno)) {
        // This error code is not included in error_reporting
        return;
    }
    throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});
$url = $_SERVER["REQUEST_URI"];

if ($url === "/robots.txt") {
    //
    http_response_code(200);
    return;
}
if ($url === "/favicon.ico") {
    //
    http_response_code(404);
    return;
}
if (0 !== strpos($url, "/https://raw.githubusercontent.com/")) {
    showMainPage();
    return;
}
$url = substr($url, 1);

$lowercase_type = explode(".", basename($url));
$lowercase_type = strtolower($lowercase_type[array_key_last($lowercase_type)]);
// var_dump("url",$url,"_GET",$_GET,"_POST",$_POST,"_REQUEST",$_REQUEST,"_SERVER",$_SERVER);
//var_dump($url);
// 
$redirect_header = 'X-Accel-Redirect: /githubusercontent_proxy/' . urlencode($url);
//$redirect_header='X-Accel-Redirect: /githubusercontent_proxy/'.$url;
if (0) {
    var_dump($redirect_header);
} else {
    header("Content-Type: text/plain; charset=utf-8");
    $requestHeaders = getallheaders();
    $problematicHeaders = array(
"Content-Length",
 "Connection", "Host", 
"Accept-Encoding",
// "X-Forwarded-For",
"content-security-policy",
"cross-origin-resource-policy",
"x-xss-protection",
);
    foreach ($problematicHeaders as $problematicHeader) {
        if (array_key_exists($problematicHeader, $requestHeaders)) {
            unset($requestHeaders[$problematicHeader]);
        }
    }
    header("Content-Type: " . fileContentType($lowercase_type));
    $ch = curl_init();
    $time_limit_seconds = 5 * 60;
    set_time_limit($time_limit_seconds);
    $curlopts = array(
        CURLOPT_URL => $url,
        CURLOPT_HEADERFUNCTION => function ($ch, $header) {
            $trimmedHeader = trim($header);
            $trimmedHeaderLowercase = strtolower($trimmedHeader);
            if (str_starts_with($trimmedHeaderLowercase, "http/")) {
                http_response_code((int)(explode(" ", $trimmedHeaderLowercase)[1]));
                return strlen($header);
            }
            $ignoreHeaders = array(
                //"content-encoding",
                "transfer-encoding",
                //"content-length",
                  "connection",
                   "host", 
                  // "accept-encoding",
                    "content-type",
"content-security-policy",
"cross-origin-resource-policy",
"x-xss-protection",
            );
            $isIgnoredHeader = false;
            foreach ($ignoreHeaders as $ignoreHeader) {
                if (str_starts_with($trimmedHeaderLowercase, $ignoreHeader)) {
                    $isIgnoredHeader = true;
                    break;
                }
            }
            if (!$isIgnoredHeader) {
                //if(false!==stripos($trimmedHeader,"content-length:"))
                header($trimmedHeader);
                //file_put_contents("debug_headers.txt", $trimmedHeader . "\n", FILE_APPEND | LOCK_EX);
            }
            return strlen($header);
        },
        CURLOPT_CONNECTTIMEOUT => 10,
        CURLOPT_TIMEOUT => $time_limit_seconds,
        CURLOPT_SSL_VERIFYPEER => false,
        CURLOPT_SSL_VERIFYHOST => false,
        //CURLOPT_ENCODING => "",
        CURLOPT_HTTPHEADER => array_map(function ($key, $value) {
            return "$key: $value";
        }, array_keys($requestHeaders), $requestHeaders),
    );
    if (!curl_setopt_array($ch, $curlopts)) {
        throw new Exception("curl_setopt_array failed: " . curl_error($ch));
    }
    $result = curl_exec($ch);
    if (curl_errno($ch) !== CURLE_OK) {
        throw new Exception("curl_exec failed: " . curl_errno($ch) . ": " . curl_strerror(curl_errno($ch)) . ": " . curl_error($ch));
    }
    curl_close($ch);
    return;
}
function showMainPage()
{
    http_response_code(200);
    header("Content-Type: text/plain; charset=utf-8");
    echo "hi!\n";
    echo "add your raw.githubusercontent.com link to the end of the url:\n";
    echo "https://rawgit.loltek.net/";
    echo "\n\nexample:\nto get: https://raw.githubusercontent.com/loltek/rawgit.loltek.net/master/src/www/script.php \ngo to:  https://rawgit.loltek.net/https://raw.githubusercontent.com/loltek/rawgit.loltek.net/master/src/www/script.php";
    echo "\n\n\n";
    echo "github repo (bugs/development/blahblah): https://github.com/loltek/rawgit.loltek.net\n";
    echo "\nsource code for this script: \n\n\n";
    readfile(__FILE__);
}

function fileContentType(string $lowercase_type): string
{
    // list extracted from nginx using
    /*
    $lines=array_values(array_filter(array_map("trim",explode("\n",$raw)),"strlen"));
    $result=[];
    foreach($lines as $line){
        $line=substr($line,0,-1);
        $tmp=explode(" ",$line,2);
        assert(count($tmp)===2);
        $type=trim($tmp[0]);
        $exts=explode(" ",trim($tmp[1]));
        foreach($exts as $ext){
            $result[trim($ext)]=trim($type);
        }
    }
    var_export($result);
    */
    $mimes = array(
        'html' => 'text/html',
        'htm' => 'text/html',
        'shtml' => 'text/html',
        'css' => 'text/css',
        'xml' => 'text/xml',
        'gif' => 'image/gif',
        'jpeg' => 'image/jpeg',
        'jpg' => 'image/jpeg',
        'js' => 'application/javascript',
        'atom' => 'application/atom+xml',
        'rss' => 'application/rss+xml',
        'mml' => 'text/mathml',
        'txt' => 'text/plain',
        'jad' => 'text/vnd.sun.j2me.app-descriptor',
        'wml' => 'text/vnd.wap.wml',
        'htc' => 'text/x-component',
        'png' => 'image/png',
        'php' => 'text/x-php; charset=utf-8',
        'tif' => 'image/tiff',
        'tiff' => 'image/tiff',
        'wbmp' => 'image/vnd.wap.wbmp',
        'ico' => 'image/x-icon',
        'jng' => 'image/x-jng',
        'bmp' => 'image/x-ms-bmp',
        'svg' => 'image/svg+xml',
        'svgz' => 'image/svg+xml',
        'webp' => 'image/webp',
        'woff' => 'application/font-woff',
        'jar' => 'application/java-archive',
        'war' => 'application/java-archive',
        'ear' => 'application/java-archive',
        'json' => 'application/json',
        'hqx' => 'application/mac-binhex40',
        'doc' => 'application/msword',
        'pdf' => 'application/pdf',
        'ps' => 'application/postscript',
        'eps' => 'application/postscript',
        'ai' => 'application/postscript',
        'rtf' => 'application/rtf',
        'm3u8' => 'application/vnd.apple.mpegurl',
        'xls' => 'application/vnd.ms-excel',
        'eot' => 'application/vnd.ms-fontobject',
        'ppt' => 'application/vnd.ms-powerpoint',
        'wmlc' => 'application/vnd.wap.wmlc',
        'kml' => 'application/vnd.google-earth.kml+xml',
        'kmz' => 'application/vnd.google-earth.kmz',
        '7z' => 'application/x-7z-compressed',
        'cco' => 'application/x-cocoa',
        'jardiff' => 'application/x-java-archive-diff',
        'jnlp' => 'application/x-java-jnlp-file',
        'run' => 'application/x-makeself',
        'pl' => 'application/x-perl',
        'pm' => 'application/x-perl',
        'prc' => 'application/x-pilot',
        'pdb' => 'application/x-pilot',
        'rar' => 'application/x-rar-compressed',
        'rpm' => 'application/x-redhat-package-manager',
        'sea' => 'application/x-sea',
        'swf' => 'application/x-shockwave-flash',
        'sit' => 'application/x-stuffit',
        'tcl' => 'application/x-tcl',
        'tk' => 'application/x-tcl',
        'der' => 'application/x-x509-ca-cert',
        'pem' => 'application/x-x509-ca-cert',
        'crt' => 'application/x-x509-ca-cert',
        'xpi' => 'application/x-xpinstall',
        'xhtml' => 'application/xhtml+xml',
        'xspf' => 'application/xspf+xml',
        'zip' => 'application/zip',
        'bin' => 'application/octet-stream',
        'exe' => 'application/octet-stream',
        'dll' => 'application/octet-stream',
        'deb' => 'application/octet-stream',
        'dmg' => 'application/octet-stream',
        'iso' => 'application/octet-stream',
        'img' => 'application/octet-stream',
        'msi' => 'application/octet-stream',
        'msp' => 'application/octet-stream',
        'msm' => 'application/octet-stream',
        'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
        'mid' => 'audio/midi',
        'midi' => 'audio/midi',
        'kar' => 'audio/midi',
        'mp3' => 'audio/mpeg',
        'ogg' => 'audio/ogg',
        'm4a' => 'audio/x-m4a',
        'ra' => 'audio/x-realaudio',
        '3gpp' => 'video/3gpp',
        '3gp' => 'video/3gpp',
        'ts' => 'video/mp2t',
        'mp4' => 'video/mp4',
        'mpeg' => 'video/mpeg',
        'mpg' => 'video/mpeg',
        'mov' => 'video/quicktime',
        'webm' => 'video/webm',
        'flv' => 'video/x-flv',
        'm4v' => 'video/x-m4v',
        'mng' => 'video/x-mng',
        'asx' => 'video/x-ms-asf',
        'asf' => 'video/x-ms-asf',
        'wmv' => 'video/x-ms-wmv',
        'avi' => 'video/x-msvideo',
    );
    if (isset($mimes[$lowercase_type])) {
        $ret = $mimes[$lowercase_type];
    } else{
        header("X-Unknown-Mime: true");
        $ret = 'application/octet-stream';
    }
    //file_put_contents('debug_header.txt', "detected content-type: $ret for {$lowercase_type}\n", FILE_APPEND | LOCK_EX);
    return $ret;
}