scrobble to last.fm

[steadfasterX]

continuing #85

@xou816

I have no plans for a last.fm integration, sorry! :/ I'd like to focus on spotify features first!

scrobbling to last.fm is a feature available in the official spotify client and the only reason why I still stay on that one instead of using spot.. so I hope you might look into this again :) 🤞

keep an eye on https://github.com/librespot-org/librespot/issues/913 though if planning to use that approach