message: fix gtl warnings
diff: @@ -3786,7 +3786,7 @@ auto get_concat_nodedef = [](DataType dtype, int num_inputs) -> NodeDef {
  }
  auto axis = ops::Placeholder(s.WithOpName("axis"), DT_INT32);
  auto concat = ops::Concat(s.WithOpName("my_concat"),
  - gtl::ArraySlice<Input>(values), axis);
  + absl::Span<const Input>(values), axis);
  return concat.operation.node()->def();
  };
  