fix: Add _registered_method to grpc ChannelStub (#614)

* fix: Add _registered_method to grpc ChannelStub

* Fix format

* Fix black

google/api_core/grpc_helpers.py

@@ -569,20 +569,42 @@ def __getattr__(self, key):
  except KeyError:
  raise AttributeError
 
- def unary_unary(self, method, request_serializer=None, response_deserializer=None):
+ def unary_unary(
+ self,
+ method,
+ request_serializer=None,
+ response_deserializer=None,
+ _registered_method=False,
+ ):
  """grpc.Channel.unary_unary implementation."""
  return self._stub_for_method(method)
 
- def unary_stream(self, method, request_serializer=None, response_deserializer=None):
+ def unary_stream(
+ self,
+ method,
+ request_serializer=None,
+ response_deserializer=None,
+ _registered_method=False,
+ ):
  """grpc.Channel.unary_stream implementation."""
  return self._stub_for_method(method)
 
- def stream_unary(self, method, request_serializer=None, response_deserializer=None):
+ def stream_unary(
+ self,
+ method,
+ request_serializer=None,
+ response_deserializer=None,
+ _registered_method=False,
+ ):
  """grpc.Channel.stream_unary implementation."""
  return self._stub_for_method(method)
 
  def stream_stream(
- self, method, request_serializer=None, response_deserializer=None
+ self,
+ method,
+ request_serializer=None,
+ response_deserializer=None,
+ _registered_method=False,
  ):
  """grpc.Channel.stream_stream implementation."""
  return self._stub_for_method(method)