image: The callback ID is bytes, not string
image: The callback ID is bytes, not string

Fixes Python 3 breakage.

kotamat/pyspotify,felix1m/pyspotify,felix1m/pyspotify,jodal/pyspotify,jodal/pyspotify,mopidy/pyspotify,jodal/pyspotify,kotamat/pyspotify,kotamat/pyspotify,mopidy/pyspotify,felix1m/pyspotify