Introduces a new plugin called "badfiles", which helps to scan for
corruption within the music collection. I've added this to
pluginsWithoutDeps and sorted the list.
Full upstream changelog can be found here:
https://github.com/sampsyo/beets/releases/tag/v1.3.15
This fixes#10376 via sampsyo/beets@225ba28.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>