cleanup unused code and mixins

src/main/java/carpet/mixins/EndCityFeatureMixin.java

@@ -2,10 +2,8 @@ package carpet.mixins;
 
 import carpet.CarpetSettings;
 import com.google.common.collect.Lists;
-//import com.mojang.datafixers.Dynamic;
 import com.mojang.serialization.Codec;
 import net.minecraft.entity.EntityType;
-import net.minecraft.world.biome.Biome;
 import net.minecraft.world.biome.SpawnSettings;
 import net.minecraft.world.gen.feature.DefaultFeatureConfig;
 import net.minecraft.world.gen.feature.EndCityFeature;
@@ -14,7 +12,6 @@ import org.spongepowered.asm.mixin.Mixin;
 
 import java.util.Collections;
 import java.util.List;
-//import java.util.function.Function;
 
 @Mixin(EndCityFeature.class)
 public abstract class EndCityFeatureMixin extends StructureFeature<DefaultFeatureConfig>