Fix: exclude admin perms from group permissions serializer (#6608)

src/paperless/serialisers.py

@@ -93,7 +93,7 @@ class UserSerializer(serializers.ModelSerializer):
 class GroupSerializer(serializers.ModelSerializer):
     permissions = serializers.SlugRelatedField(
         many=True,
-        queryset=Permission.objects.all(),
+        queryset=Permission.objects.exclude(content_type__app_label="admin"),
         slug_field="codename",
     )