fix(production plan): filter sales orders by item

(cherry picked from commit bfff945fb1)

erpnext/manufacturing/doctype/production_plan/production_plan.js

@@ -24,6 +24,7 @@ frappe.ui.form.on("Production Plan", {
 				query: "erpnext.manufacturing.doctype.production_plan.production_plan.sales_order_query",
 				filters: {
 					company: frm.doc.company,
+					item_code: frm.doc.item_code,
 				},
 			};
 		});

erpnext/manufacturing/doctype/production_plan/production_plan.py

@@ -1994,6 +1994,9 @@ def sales_order_query(doctype=None, txt=None, searchfield=None, start=None, page
 	if filters.get("sales_orders"):
 		query = query.where(so_table.name.isin(filters.get("sales_orders")))
 
+	if filters.get("item_code"):
+		query = query.where(table.item_code == filters.get("item_code"))
+
 	if txt:
 		query = query.where(table.parent.like(f"%{txt}%"))