cleanup unused code and mixins

src/main/java/carpet/helpers/HopperCounter.java

@@ -11,7 +11,6 @@ import net.minecraft.text.BaseText;
 import net.minecraft.text.TranslatableText;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.world.World;
-import net.minecraft.world.dimension.DimensionType;
 
 import java.util.ArrayList;
 import java.util.Collections;