[FIX] l10n_ar_withholding: Clean up WH Payment Type

Clean up field value when is not used, this because is only
show when some conditions applies, if not we need to clear it to
avoid having wrong data on taxes.

We want to behave as an onchange, to se change the field to a compute
one, in this case stored and also can be edit by the user

closes odoo/odoo#156808

Signed-off-by: Josse Colpaert <jco@odoo.com>

addons/l10n_ar_withholding/models/account_tax.py

@@ -1,5 +1,5 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
-from odoo import fields, models
+from odoo import api, fields, models
 
 
 class AccountTax(models.Model):
@@ -7,7 +7,13 @@ class AccountTax(models.Model):
     _inherit = 'account.tax'
 
     l10n_ar_withholding_payment_type = fields.Selection(
-        [('supplier', 'Supplier'), ('customer', 'Customer')], 'Argentinean Withholding type')
+        [('supplier', 'Supplier'), ('customer', 'Customer')], 'Argentinean Withholding type',
+        compute="_compute_l10n_ar_withholding_payment_type", store=True, readonly=False)
+
     l10n_ar_withholding_sequence_id = fields.Many2one(
         'ir.sequence', 'Withholding Number Sequence', copy=False, check_company=True,
         help='If no sequence provided then it will be required for you to enter withholding number when registering one.')
+
+    @api.depends('type_tax_use', 'country_code')
+    def _compute_l10n_ar_withholding_payment_type(self):
+        self.filtered(lambda x: not x.l10n_ar_withholding_payment_type or x.type_tax_use != 'none' or x.country_code != 'AR').l10n_ar_withholding_payment_type = False