tests: accept py3 output in test_list_valued_setting_update

The old behaviour seems completely broken and useless and thus evidently unused
... but the new result seems slightly better.

kallithea/tests/models/test_settings.py

@@ -39,8 +39,8 b' def test_list_valued_setting_update():'
         # Assign back setting value.
         setting.app_settings_value = setting.app_settings_value
         # Quirk: value is stringified on write and listified on read.
-        assert setting.app_settings_value == ["[u'spam']"]
+        assert setting.app_settings_value == ["['spam']"]
         setting.app_settings_value = setting.app_settings_value
-        assert setting.app_settings_value == ["[u\"[u'spam']\"]"]
+        assert setting.app_settings_value == ["[\"['spam']\"]"]
     finally:
         Session().delete(setting)