fix fixture

Author: blink1073

libs/langchain-mongodb/tests/unit_tests/test_index.py

@@ -13,7 +13,7 @@
 
 
 @pytest.fixture
-def collection() -> Generator[None, Collection]:
+def collection() -> Generator[None, None, Collection]:
     """Collection on MongoDB Cluster, not an Atlas one."""
     client: MongoClient = MongoClient()
     yield client["db"]["collection"]