chore: Remove self-assignment

src/main/java/cz/jzitnik/game/entities/items/Item.java

@@ -32,7 +32,6 @@ public class Item {
         this.type = type;
         this.sprite = sprite;
         this.toolVariant = Optional.of(toolVariant);
-        this.miningDecrease = miningDecrease;
         this.durability = durability;
         this.stackable = stackable;
         this.dealDamage = dealDamage;