[accounting] New API migration

- Task: https://www.odoo.com/web/#id=9955&view_type=form&model=project.task&action=333&active_id=131
- Pad: https://pad.odoo.com/p/r.Uy4wEA7I4G4GwPaU
Please replace the `<>` by `!=`. (`<>` is old-style Python and won't work in Python 3)