[FIX] account: Updating currency on Vendor bill

Steps to reproduce the bug:

- Enable Multi-Currencies and Multi-Companies
- Create a vendor bill
- Remove the default journal
- Set an other currencies

Bug:

A traceback was raised

opw:2350490

closes odoo/odoo#59469

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>