Automated change: Fix sanity tests

src/python/grpcio/grpc/aio/_metadata.py

diff --git a/src/python/grpcio/grpc/aio/_metadata.py b/src/python/grpcio/grpc/aio/_metadata.py
index 8a885d7..4be094a 100644
--- a/src/python/grpcio/grpc/aio/_metadata.py
+++ b/src/python/grpcio/grpc/aio/_metadata.py
@@ -46,6 +46,7 @@
         * Supports an immutable view of the data
         * Allows partial mutation on the data without recreating the new object from scratch.
     """
+
     _metadata: OrderedDict[MetadataKey, List[MetadataValue]]
 
     def __init__(self, *args: MetadatumType) -> None: