fixup! feat(firestore): *DocumentReference: add types

Author: tharvik

packages/google-cloud-firestore/google/cloud/firestore_v1/base_document.py

@@ -133,7 +133,7 @@ def __eq__(self, other: object) -> bool:
             return NotImplemented
 
     def __hash__(self) -> int:
-        return hash(self._path) + hash(self._client)
+        return hash((self._path, self._client))
 
     def __ne__(self, other) -> bool:
         """Inequality check against another instance.