fix: Avoid high memory usage when pruning a lot of skipped uploads

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2512>

api/funkwhale_api/music/management/commands/prune_skipped_uploads.py

@@ -22,7 +22,7 @@ class Command(BaseCommand):
     @transaction.atomic
     def handle(self, *args, **options):
         skipped = models.Upload.objects.filter(import_status="skipped")
-        count = len(skipped)
+        count = skipped.count()
         if options["force"]:
             skipped.delete()
             print(f"Deleted {count} entries from the database.")

changes/changelog.d/2136.bugfix

@@ -0,0 +1 @@
+Fix Prune skipped uploads is OOM killed (#2136)