🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

google/cloud/bigtable_v2/services/bigtable/transports/__init__.py

@@ -28,12 +28,14 @@
 _transport_registry = OrderedDict() # type: Dict[str, Type[BigtableTransport]]
 _transport_registry["grpc"] = BigtableGrpcTransport
 _transport_registry["grpc_asyncio"] = BigtableGrpcAsyncIOTransport
+_transport_registry["pooled_grpc_asyncio"] = PooledBigtableGrpcAsyncIOTransport
 _transport_registry["rest"] = BigtableRestTransport
 
 __all__ = (
  "BigtableTransport",
  "BigtableGrpcTransport",
  "BigtableGrpcAsyncIOTransport",
+ "PooledBigtableGrpcAsyncIOTransport",
  "BigtableRestTransport",
  "BigtableRestInterceptor",
 )