message: Fix compile of libcaf_python
diff: @@ -482,13 +482,13 @@ pybind11::tuple tuple_from_message(const type_erased_tuple& msg) {
  if (str_ptr == nullptr) {
  set_py_exception("Unable to extract element #", i, " from message: ",
  "could not get portable name of ", rtti.second->name());
  - return {};
  + return pybind11::tuple{};
  }
  auto kvp = bindings.find(*str_ptr);
  if (kvp == bindings.end()) {
  set_py_exception(R"(Unable to add element of type ")",
  *str_ptr, R"(" to message: type is unknown to CAF)");
  - return {};
  + return pybind11::tuple{};
  }
  auto obj = kvp->second->to_object(msg, i);
  PyTuple_SetItem(result.ptr(), static_cast<int>(i), obj.release().ptr());
  