A simple Python HTTP server that can handle mime types properly.

Server.py

#!/usr/bin/env python3

import http.server
import socketserver

HOST = "localhost"
PORT = 8000


class HttpRequestHandler(http.server.SimpleHTTPRequestHandler):
    extensions_map = {".manifest": "text/cache-manifest"}

    def version_string(self):
        return "Apache/1.3.0 (Win32)"


try:
    with socketserver.TCPServer((HOST, PORT), HttpRequestHandler) as httpd:
        print(f"serving at http://{HOST}:{PORT}")
        httpd.serve_forever()
except KeyboardInterrupt:
    pass

Updated with suggestion from @jan25 here.

Since Python 3.9, the extensions_map parameter is used solely to override a vast list of default values with custom MIME types, mostly rendering this script superfluous. Redundant MIME types have been removed.

Additionally, I added an override for the Server header in this version.