[FIX] account: Fix non-determinist matching-rules tests

If the current date changes when creating the invoices (e.g. nightly builds)
the results are not always in the same order because the matching rules propositions are
sorted by date in the descendant order.

closes odoo/odoo#37653

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

addons/account/tests/test_reconciliation_matching_rules.py

 # -*- coding: utf-8 -*-
+from odoo import fields
 from odoo.addons.account.tests.account_test_classes import AccountingTestCase
 from odoo.tests.common import Form
 from odoo.tests import tagged
@@ -9,6 +10,7 @@ class TestReconciliationMatchingRules(AccountingTestCase):
     def _create_invoice_line(self, amount, partner, type):
         ''' Create an invoice on the fly.'''
         invoice_form = Form(self.env['account.move'].with_context(default_type=type))
+        invoice_form.invoice_date = fields.Date.from_string('2019-09-01')
         invoice_form.partner_id = partner
         with invoice_form.invoice_line_ids.new() as invoice_line_form:
             invoice_line_form.name = 'xxxx'