[FIX] account_payment_group: The method '_company_default_get' on res…

….company is deprecated

closes #387

Related: ingadhoc/odoo-academic#91
Signed-off-by: Juan José Scarafía <jjs@adhoc.com.ar>

account_payment_group/models/account_payment_receiptbook.py

@@ -70,8 +70,7 @@ class AccountPaymentReceiptbook(models.Model):
         'res.company',
         'Company',
         required=True,
-        default=lambda self: self.env[
-            'res.company']._company_default_get('account.payment.receiptbook')
+        default=lambda self: self.env.company
     )
     prefix = fields.Char(
         'Prefix',