Test all supported python version for stable branch

As Tempest is branchless and needs to support older
supported stable branches, let's test it with all the
python version supported in those supported stable branches.
For that, we need to explicitly dd the py jobs instead of using
the template. This way, we will explicitly know that we are testing
all supported python versions when the new release template bumps the
min python version in the template.

In Yoga testing, we are making py3.9 job to run as voting, so
adding py3.9 job as voting.

Change-Id: I422da8da06509e529f4091e21cdc3d392d3cf910

setup.cfg

@@ -18,6 +18,7 @@ classifier =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: Implementation :: CPython
 

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = pep8,py36,py38,bashate,pip-check-reqs
+envlist = pep8,py36,py39,bashate,pip-check-reqs
 minversion = 3.18.0
 skipsdist = True
 ignore_basepython_conflict = True

zuul.d/project.yaml

@@ -3,11 +3,15 @@
       - check-requirements
       - integrated-gate-py3
       - openstack-cover-jobs
-      - openstack-python3-xena-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
     check:
       jobs:
+        - openstack-tox-pep8
+        - openstack-tox-py36
+        - openstack-tox-py37
+        - openstack-tox-py38
+        - openstack-tox-py39
         - tempest-full-parallel:
             # Define list of irrelevant files to use everywhere else
             irrelevant-files: &tempest-irrelevant-files
@@ -120,6 +124,11 @@
             irrelevant-files: *tempest-irrelevant-files-2
     gate:
       jobs:
+        - openstack-tox-pep8
+        - openstack-tox-py36
+        - openstack-tox-py37
+        - openstack-tox-py38
+        - openstack-tox-py39
         - tempest-slow-py3:
             irrelevant-files: *tempest-irrelevant-files
         - neutron-ovs-grenade-multinode: