Listenbrainz and/or Libre.fm support

[iparr]

See:

• https://listenbrainz.org/
• https://libre.fm/

Sorry, I don't know what it takes to add support for these services in a similar manner. But support would be nice, as last.fm always feels a little bit like it's on the edge of disappearing completely!

(Nice to see a bit of activity on this repo btw, great work)