Create openstack-tox-py36 job

To replace the legacy-python-swiftclient-python36-fedora-26 job, create
a new openstack-tox-py36 job.

Change-Id: Ie3c37f7bcc6d69a6522e1585d76d310aebcd9263

zuul.d/jobs.yaml

@@ -273,6 +273,24 @@
       tox_envlist: py35
       bindep_profile: test py35
 
+- job:
+    name: openstack-tox-py36
+    parent: openstack-tox
+    nodeset: fedora-26
+    description: |
+
+      Run unit tests for an OpenStack Python project under cPython
+      version 3.6. This test runs on a Fedora 26 node.
+
+      Uses tox with the ``py36`` environment.
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^releasenotes/.*$
+    vars:
+      tox_envlist: py36
+      bindep_profile: test py36
+
 - job:
     name: openstack-tox-pypy
     parent: openstack-tox