fix: search not working for so in the Production Plan (#36459)

fix: search not working for so

erpnext/manufacturing/doctype/production_plan/production_plan.py

@@ -1731,7 +1731,7 @@ def sales_order_query(
 		query = query.where(so_table.name.isin(filters.get("sales_orders")))
 
 	if txt:
-		query = query.where(table.item_code.like(f"{txt}%"))
+		query = query.where(table.parent.like(f"%{txt}%"))
 
 	if page_len:
 		query = query.limit(page_len)