Adding back the level up sound being played that was accidentally rem…

…oved in the previous commit

src/modes/battle/battle_finish.cpp

@@ -111,6 +111,7 @@ void CharacterGrowth::UpdateGrowthData() {
 
         if (level_gained == true) {
             _experience_levels_gained++;
+            AudioManager->PlaySound("snd/levelup.wav");
 
             // New skills are only found in growth data when the character has reached a new level
             // Note that the character's new skills learned container will be cleared upon the next