Update attributes

Hi! I hope I was able to detect all attributes that needed to be added/removed, so this is what this PR is about. You may notice that 'genres' assertions had to be updated due to a data inconsistency on Spotifys end (for mor e info: https://developer.spotify.com/web-api/migration-guide/#comment-1591237278). Thanks!

On a side note, I notice that the builds are now failing since we're now using '.to_h' which seems to be available on a most recent version of Ruby. I see two options: remove 2.0 support from travis.yml or if the goal is to have backwards compatibility, don't use '.to_h'.