Remove six

Python 2 is no longer supported, thus usage of six can be removed.

Change-Id: I60259f7b326ac862409b4d8a0591859a0f070e8b
diff --git a/ironic_tempest_plugin/tests/api/admin/test_nodes.py b/ironic_tempest_plugin/tests/api/admin/test_nodes.py
index 85c31e0..d6b262d 100644
--- a/ironic_tempest_plugin/tests/api/admin/test_nodes.py
+++ b/ironic_tempest_plugin/tests/api/admin/test_nodes.py
@@ -11,7 +11,6 @@
 #    under the License.
 
 from oslo_utils import uuidutils
-import six
 from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
@@ -136,7 +135,7 @@
         body = self.client.get_node_boot_device(self.node['uuid'])
         self.assertIn('boot_device', body)
         self.assertIn('persistent', body)
-        self.assertIsInstance(body['boot_device'], six.string_types)
+        self.assertIsInstance(body['boot_device'], str)
         self.assertIsInstance(body['persistent'], bool)
 
     @decorators.idempotent_id('3622bc6f-3589-4bc2-89f3-50419c66b133')
diff --git a/ironic_tempest_plugin/tests/api/base.py b/ironic_tempest_plugin/tests/api/base.py
index d78f74a..c541dd3 100644
--- a/ironic_tempest_plugin/tests/api/base.py
+++ b/ironic_tempest_plugin/tests/api/base.py
@@ -10,7 +10,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import six
+import functools
+
 from tempest import config
 from tempest.lib.common import api_version_utils
 from tempest.lib.common.utils import data_utils
@@ -41,7 +42,7 @@
     """Decorator that adds resources to the appropriate cleanup list."""
 
     def decorator(f):
-        @six.wraps(f)
+        @functools.wraps(f)
         def wrapper(cls, *args, **kwargs):
             resp, body = f(cls, *args, **kwargs)