[FIX] Account: account_field field typo

the field data-max is supposed to be stored in the database.
Currently, the arg is 'stored=True' which is not recognised by the orm.
This fix ensures the field is correctly sotred and thus not computed at reading.

addons/account/models/account_move.py

@@ -1431,7 +1431,7 @@ class AccountPartialReconcile(models.Model):
     company_id = fields.Many2one('res.company', related='debit_move_id.company_id', store=True, string='Currency')
     full_reconcile_id = fields.Many2one('account.full.reconcile', string="Full Reconcile", copy=False)
     max_date = fields.Date(string='Max Date of Matched Lines', compute='_compute_max_date',
-        readonly=True, copy=False, stored=True,
+        readonly=True, copy=False, store=True,
         help='Technical field used to determine at which date this reconciliation needs to be shown on the aged receivable/payable reports.')
 
     @api.multi