Update tests/test_utils_metaclasses.py

tests/test_utils_metaclasses.py

@@ -1,7 +1,7 @@
 import pytest
 from abc import abstractmethod
 from slic.utils.metaclasses import combine_classes, RegistryABC
-
+from slic.utils.registry import instances
 
 # Test combine two simple classes with unique methods
 class A: