API: Fix deleting checkin-lists (Z#23170525) (PRETIXEU-AS5) (#4600)

src/pretix/api/views/checkin.py

@@ -143,7 +143,9 @@ class CheckinListViewSet(viewsets.ModelViewSet):
             data=self.request.data
         )
 
+    @transaction.atomic
     def perform_destroy(self, instance):
+        instance.checkins.all().delete()
         instance.log_action(
             'pretix.event.checkinlist.deleted',
             user=self.request.user,