Follow isort formatting

issue10928

tests/test_carrier.py

@@ -1,6 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 import unittest
+
 import trytond.tests.test_tryton
 from trytond.tests.test_tryton import ModuleTestCase