Use unittest.mock instead of third party mock

Now that we no longer support py27, we can use the standard library
unittest.mock module instead of the third party mock lib.

Change-Id: I29a92ee5a0eeffcf0f2dc1aba1229cf9a7075b25
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

test-requirements.txt

@@ -4,7 +4,6 @@
 
 fixtures>=3.0.0 # Apache-2.0/BSD
 coverage!=4.4,>=4.0 # Apache-2.0
-mock>=2.0.0 # BSD
 testtools>=2.2.0 # MIT
 hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0

tricircleclient/tests/unit/fakes.py

@@ -14,8 +14,7 @@
 #
 
 import sys
-
-import mock
+from unittest import mock
 
 
 class FakeStdout(object):

tricircleclient/tests/unit/v1/test_jobs_cli.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from tricircleclient import constants
 from tricircleclient.tests.unit import utils

tricircleclient/tests/unit/v1/test_pods_cli.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from tricircleclient.tests.unit import utils
 from tricircleclient.v1 import pods_cli

tricircleclient/tests/unit/v1/test_routings_cli.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from tricircleclient.tests.unit import utils
 from tricircleclient.v1 import routings_cli