Add support for Gpodder client

[hydrian]

Looking for a linux platform podcast player that supports this API. gpodder seems the obvious choice since it obviously supports the API.

The support may even already exist, user just need documentation on how to set it up.

[thrillfall]

You need to ask this at https://github.com/gpodder/gpodder.

[ernestask]

gpodder/gpodder#1251 (comment)

[thrillfall]

Any contributions that make this app more useful (to more users) are always welcome.