accounting: round accounting lines after building payment transaction

Like we do on invoice and other accounting transaction we build

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/PaymentTransaction_postGeneration.py

 from Products.ERP5Type.Message import translateString
 
 payment_transaction = context
+payment_transaction.AccountingTransaction_roundDebitCredit()
 
 # initialize accounting_workflow to planned state
 if payment_transaction.getSimulationState() == "draft":