replace include guards with pragma once

src/frontend/menu.hpp

@@ -1,5 +1,4 @@
-#ifndef FRONTEND_MENU_MENU_HPP_
-#define FRONTEND_MENU_MENU_HPP_
+#pragma once
 
 #include "data/dynamic.hpp"
 #include "graphics/ui/elements/Menu.hpp"
@@ -29,5 +28,3 @@ namespace menus {
 
     bool call(Engine* engine, runnable func);
 }
-
-#endif // FRONTEND_MENU_MENU_HPP_