Fix: Handle leap year calculation for valid dates in February

--HG-- branch : 16.0

• Fix ci error : ValueError: day is out of range for month
• Odoo task : MO16-00745 - Date non valide pour année non bissextile tests account_period

tests/test_account_period.py

@@ -65,7 +65,7 @@
         self.assertEqual(accentries.mapped("period_id").id, period_today.id)
 
         # Force a date on the invoice; ensure period selection follows it.
-        date_2017 = self.today.replace(year=2017)
+        date_2017 = self.today + relativedelta(year=2017)
         period_2017 = self.Period.find(date=date_2017)
         accdoc_2017 = self._make_invoice(
             invoice_date=date_2017, company=period_2017.company_id