StatsManager: Don't fire OnManaChanged without changes

Assets/Scripts/StatsManager.cs

@@ -108,7 +108,10 @@ public class StatsManager : MonoBehaviour, IRoundCallback
         }
         var previousMana = currentMana;
         currentMana += delta;
-        manaChangeCallbacks.ForEach(c => c.OnManaChanged(previousMana, currentMana));
+        if (delta != 0)
+        {
+            manaChangeCallbacks.ForEach(c => c.OnManaChanged(previousMana, currentMana));
+        }
         return true;
     }