[FIX] account: reversed entry in the future is posted

Install Accounting, create a journal entry, post it, reverse it with
a date in the future.

The reverse entry will be posted, instead it should stay a draft (with
the appropriate 'auto_post' set to True)

opw-2083121

closes odoo/odoo#38802

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>