Cloudflare Worker YouTube RSS Proxy

Usage:
  - GET ?channel_id=UCbCCUH8S3yhlm7__rhxR2QQ
  - GET ?url=https://www.youtube.com/feeds/videos.xml?channel_id=UCbCCUH8S3yhlm7__rhxR2QQ
Notes:
  - CORS enabled (Access-Control-Allow-Origin: *)
  - Only YouTube /feeds/* endpoints are allowed via url=