erp5_travel_expense: Confirm Purchase Transaction instead of Stopping it

bt5/erp5_travel_expense/SkinTemplateItem/portal_skins/erp5_hr_request/ExpenseValidationRequest_createPurchaseTransaction.py

@@ -60,6 +60,6 @@ except ValidationFailed, error_message:
     context.getAbsoluteUrl(),
     message
     )
-transaction.stop()
+transaction.confirm()
 
 return transaction.getRelativeUrl()