Changes
* The blocklet now works with any media player that supports the MPRIS D-Bus interface, not only the Spotify app. A new required parameter `player` was introduced. To indicate this change, the blocklet was renamed from `i3blocks-spotify-persist` to `i3blocks-mpris`.
* The minimum Python version was bumped to 3.6.
Fixes
* The `PlaybackStatus` and `Metadata` properties is now cached to properly handle the `PropertiesChanged` signal. There was no issue with the Spotify app purely by chance.
* Fixed erroneous `init_player()` logic.