Fixed bad format date when no payment

easy_my_coop/models/account_invoice.py

@@ -178,7 +178,7 @@ class AccountInvoice(models.Model):
             ):
                 # take the effective date from the payment.
                 # by default the confirmation date is the payment date
-                effective_date = datetime.now().strftime("%d/%m/%Y")
+                effective_date = datetime.now()
 
                 if invoice.payment_move_line_ids:
                     move_line = invoice.payment_move_line_ids[0]