fix: modify query to fetch valid return qty

erpnext/stock/doctype/delivery_note/delivery_note.py

@@ -795,12 +795,14 @@ def get_returned_qty_map(delivery_note):
 	"""returns a map: {so_detail: returned_qty}"""
 	returned_qty_map = frappe._dict(
 		frappe.db.sql(
-			"""select dn_item.dn_detail, abs(dn_item.qty) as qty
+			"""select dn_item.dn_detail, sum(abs(dn_item.qty)) as qty
 		from `tabDelivery Note Item` dn_item, `tabDelivery Note` dn
 		where dn.name = dn_item.parent
 			and dn.docstatus = 1
 			and dn.is_return = 1
 			and dn.return_against = %s
+			and dn_item.qty <= 0
+			group by dn_item.item_code
 	""",
 			delivery_note,
 		)