gpodder: package with support for the youtube-dl extension

gpodder ships support for subscribing to youtube feeds,
leveraging `youtube-dl` (or yt-dlp) for downloading items.
enable this from hamburger menu > extensions > youtube-dl.

see: <https://gpodder.github.io/docs/extensions/youtubedl.html>

pkgs/by-name/gp/gpodder/package.nix

@@ -63,6 +63,7 @@ python311Packages.buildPythonApplication rec {
     podcastparser
     html5lib
     mutagen
+    yt-dlp  # for use by gpodder's builtin "youtube-dl" extension
   ];
 
   makeFlags = [