Was changed within upstream commit abc0c2d2a2a0bfb0214798ed6bca9d59359b39f8.
The sole reason this worked was that `settings.storage.media.file.path`
pointed to `./media`, relative to `/var/lib/authentik`.
Update our config accordingly.
The new migration in tenant_files.py references a MEDIA_ROOT directory
based on its own path, which in our case is in the read-only /nix/store.
We need it to refer to the actual authentik state directory instead,
which defaults to /var/lib/authentik/media in module.nix