fix: use enum values for string representation of RelationshipProperty

Author: matmoncon

pyneo4j_ogm/fields/relationship_property.py

@@ -287,8 +287,8 @@ def __ne__(self, other: Any) -> bool:
     def __repr__(self) -> str:
         return (
             f"{self.__class__.__name__}(target_model_name={self._target_model_name}, "
-            f"relationship_model={self._relationship_model_name}, direction={self._direction}, "
-            f"cardinality={self._cardinality}, allow_multiple={self._allow_multiple})"
+            f"relationship_model={self._relationship_model_name}, direction={self._direction.value}, "
+            f"cardinality={self._cardinality.value}, allow_multiple={self._allow_multiple})"
         )
 
     def __str__(self) -> str: