docs: def cover_update(self, photo, **kwds):
          """
          Endpoint: /album/<album_id>/cover/<photo_id>/update.json
  
          Update the cover photo of this album.
          """
          result = self._client.album.cover_update(self, photo, **kwds)
          self._replace_fields(result.get_fields())
          self._update_fields_with_objects()