New Features

• get_artist(channelId)
  returns a dictionary with lists of songs, albums, singles, videos on the artist page and info to get more songs/albums if available (i.e. the playlistId)

• get_artist_albums(channelId, params)
  gets singles or albums by an artist. the required params are provided by get_artist

• get_album(browseId)
  gets all songs for an album

Changes

• Only a cookie is now needed for authentication. Other headers are left out or dynamically generated
• Encode filename with UTF-8 before upload
• Fix playlist items error when artist/album missing
• Add filetype check for uploads
• Breaking: setup() now requires a filepath parameter, returns a credential string unless storage filepath is provided
• YTMusic() now accepts either a filepath or a JSON string: youtube_auth = YTMusic("<json_string>")