message: Update python_object_to_proto_visitor.py
  Changed test key for FullArgSpec to check for `varkw`, replacing the old ArgSpec key `keywords`
diff: @@ -49,7 +49,7 @@ def _SanitizedArgSpec(obj):
  output_string = ''
  unsanitized_arg_spec = tf_inspect.getfullargspec(obj)
  - for clean_attr in ('args', 'varargs', 'keywords'):
  + for clean_attr in ('args', 'varargs', 'varkw'):
  output_string += '%s=%s, ' % (clean_attr,
  getattr(unsanitized_arg_spec, clean_attr))
  