Remove all usage of six library

Replace six with Python 3 style code.

Change-Id: Ie0da4c882847268a58ab20f0fbc82fc8cf658297

cinder_tempest_plugin/services/consistencygroups_client.py

@@ -14,10 +14,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import http.client as http_client
 import time
 
 from oslo_serialization import jsonutils as json
-from six.moves import http_client
 from tempest.lib.common import rest_client
 from tempest.lib import exceptions as lib_exc
 

requirements.txt

@@ -4,6 +4,5 @@
 
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 oslo.config>=5.1.0 # Apache-2.0
-six>=1.10.0 # MIT
 oslo.serialization!=2.19.1,>=2.18.0 # Apache-2.0
 tempest>=17.1.0 # Apache-2.0