Use constants for a few magic numbers in rules

src/main/java/carpet/mixins/PistonStructureResolver_pushLimitMixin.java

@@ -0,0 +1,17 @@
+package carpet.mixins;
+
+import carpet.CarpetSettings;
+import net.minecraft.world.level.block.piston.PistonStructureResolver;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.Constant;
+import org.spongepowered.asm.mixin.injection.ModifyConstant;
+
+@Mixin(value = PistonStructureResolver.class, priority = 420)  // piston push limit is important for carpet
+public class PistonStructureResolver_pushLimitMixin
+{
+    @ModifyConstant(method = "addBlockLine", constant = @Constant(intValue = PistonStructureResolver.MAX_PUSH_DEPTH), expect = 3)
+    private int pushLimit(int original)
+    {
+        return CarpetSettings.pushLimit;
+    }
+}