fix: union test for 3.10

Signed-off-by: Erik Wrede <erikwrede2@gmail.com>

Author: erikwrede

graphene_sqlalchemy/tests/test_converter.py

@@ -163,7 +163,8 @@ def prop_method_2() -> ShoppingCartType | PetType:
     field_type_1 = get_hybrid_property_type(prop_method).type
     field_type_2 = get_hybrid_property_type(prop_method_2).type
 
-    assert isinstance(field_type_1, graphene.Union)
+    assert issubclass(field_type_1, graphene.Union)
+    assert field_type_1._meta.types == [PetType, ShoppingCartType]
     assert field_type_1 is field_type_2