fix infinite recursion error

previously there was an almost silent error because the update function was called every time. Now it should be fixed.

src/bonsai/bonsai/tool/cost.py

@@ -987,6 +987,7 @@ class Cost(bonsai.core.tool.Cost):
     def disable_editing_cost_item_parent(cls) -> None:
         props = cls.get_cost_props()
         props.active_cost_item_id = 0
+        if props.change_cost_item_parent == True:
             props.change_cost_item_parent = False
 
     @classmethod