test: Purchase Order with Unit Price Items

- chore: Fix error message in accounts controller

(cherry picked from commit eea758f5b2)

# Conflicts:
#	erpnext/buying/doctype/purchase_order/test_purchase_order.py
#	erpnext/buying/doctype/supplier_quotation/test_supplier_quotation.py

erpnext/controllers/accounts_controller.py

@@ -3746,9 +3746,9 @@ def update_child_qty_rate(parent_doctype, trans_items, parent_doctype_name, chil
 		)
 		if amount_below_billed_amt and row_rate > 0.0:
 			frappe.throw(
-				_("Row #{0}: Cannot set Rate if amount is greater than billed amount for Item {1}.").format(
-					child_item.idx, child_item.item_code
-				)
+				_(
+					"Row #{0}: Cannot set Rate if the billed amount is greater than the amount for Item {1}."
+				).format(child_item.idx, child_item.item_code)
 			)
 		else:
 			child_item.rate = row_rate