[select] Return StringRef from current_option() (#13095)

esphome/components/api/api_connection.cpp

@@ -914,7 +914,7 @@ uint16_t APIConnection::try_send_select_state(EntityBase *entity, APIConnection
                                               bool is_single) {
   auto *select = static_cast<select::Select *>(entity);
   SelectStateResponse resp;
-  resp.state = StringRef(select->current_option());
+  resp.state = select->current_option();
   resp.missing_state = !select->has_state();
   return fill_and_encode_entity_state(select, resp, SelectStateResponse::MESSAGE_TYPE, conn, remaining_size, is_single);
 }