Looks like custom slave servers of MB.org for some reason return the `score` parameter for search results as strings instead of integers. This currently let's Picard crash when loading an album.

While it is probably wrong for the servers to return data this way, Picard should be able to handle this case cleanly without crashing.

See discussion at https://community.metabrainz.org/t/picard-2-1-3-freezes-with-slave-server/422198/6