Only check Secret Lab/Time Trial/NDM for slowdown if ingame_titlemode

This is already done for invincibility. It's kind of unnecessary, but
it's just to make sure if for some reason in the future variables like
insecretlab/intimetrial/nodeathmode don't get reset when exiting to the
menu.

desktop_version/src/Input.cpp

@@ -514,7 +514,7 @@ void menuactionpress()
             break;
         case 4:
             //change game speed
-            if (!game.insecretlab && !game.intimetrial && !game.nodeathmode)
+            if (!game.ingame_titlemode || (!game.insecretlab && !game.intimetrial && !game.nodeathmode))
             {
                 game.createmenu(Menu::setslowdown);
                 map.nexttowercolour();