temporary fix for backend_ tests

Author: timgraham

django_mongodb_backend/features.py

@@ -595,6 +595,7 @@ def django_test_expected_failures(self):
     def django_test_skips(self):
         skips = super().django_test_skips
         skips.update(self._django_test_skips)
+        self.mongodb_version  # noqa: B018 temporary fix for backend_ tests
         return skips
 
     @cached_property