Remove all usage of six library

Replace six with Python 3 style code.

Change-Id: I724eba28d1a88317655f9cb7da94716772cd01ab
diff --git a/manila_tempest_tests/tests/scenario/manager.py b/manila_tempest_tests/tests/scenario/manager.py
index 1fa03f4..947d0e6 100644
--- a/manila_tempest_tests/tests/scenario/manager.py
+++ b/manila_tempest_tests/tests/scenario/manager.py
@@ -20,7 +20,6 @@
 from oslo_log import log
 from oslo_utils import netutils
 from oslo_utils import uuidutils
-import six
 from tempest.common import compute
 from tempest.common import image as common_image
 from tempest.common.utils.linux import remote_client
@@ -630,7 +629,7 @@
             try:
                 return subnets_client.create_subnet(**subnet)
             except lib_exc.Conflict as e:
-                if 'overlaps with another subnet' not in six.text_type(e):
+                if 'overlaps with another subnet' not in str(e):
                     raise
 
         result = None
diff --git a/manila_tempest_tests/tests/scenario/manager_share.py b/manila_tempest_tests/tests/scenario/manager_share.py
index d68ab04..657b1f1 100644
--- a/manila_tempest_tests/tests/scenario/manager_share.py
+++ b/manila_tempest_tests/tests/scenario/manager_share.py
@@ -14,10 +14,9 @@
 #    under the License.
 
 from tempfile import mkstemp
+from urllib.request import urlopen
 
 from oslo_log import log
-import six
-from six.moves.urllib.request import urlopen
 from tempest.common import waiters
 from tempest import config
 from tempest.lib.common.utils import data_utils
@@ -288,7 +287,7 @@
         # original implementation depends on CONF.compute.ssh_auth_method
         # option.
         server_or_ip = kwargs['server_or_ip']
-        if isinstance(server_or_ip, six.string_types):
+        if isinstance(server_or_ip, str):
             ip = server_or_ip
         else:
             addr = server_or_ip['addresses'][
diff --git a/manila_tempest_tests/tests/scenario/test_share_extend.py b/manila_tempest_tests/tests/scenario/test_share_extend.py
index f4dce61..d6a23d0 100644
--- a/manila_tempest_tests/tests/scenario/test_share_extend.py
+++ b/manila_tempest_tests/tests/scenario/test_share_extend.py
@@ -13,7 +13,6 @@
 import ddt
 from oslo_log import log as logging
 from oslo_utils import units
-import six
 from tempest import config
 from tempest.lib import decorators
 from tempest.lib import exceptions
@@ -133,7 +132,7 @@
                                                       block_count,
                                                       '/dev/urandom')
         except exceptions.SSHExecCommandFailed as e:
-            if 'stale file handle' in six.text_type(e).lower():
+            if 'stale file handle' in str(e).lower():
                 LOG.warning("Client was disconnected during extend process")
                 self.unmount_share(remote_client)
                 self.mount_share(mount_location, remote_client)
diff --git a/manila_tempest_tests/tests/scenario/test_share_shrink.py b/manila_tempest_tests/tests/scenario/test_share_shrink.py
index b4bfcd5..a4e59e8 100644
--- a/manila_tempest_tests/tests/scenario/test_share_shrink.py
+++ b/manila_tempest_tests/tests/scenario/test_share_shrink.py
@@ -13,7 +13,6 @@
 import time
 
 from oslo_log import log as logging
-import six
 from tempest import config
 from tempest.lib import decorators
 from tempest.lib import exceptions
@@ -146,7 +145,7 @@
                                                        new_size=new_size)
                 except exceptions.BadRequest as e:
                     if ('New size for shrink must be less than current size'
-                            in six.text_type(e)):
+                            in str(e)):
                         break
 
             time.sleep(check_interval)