Re-add python 3.6 functional testing

We have updated the yoga testing runtime to keep the
py36 testing.

- https://review.opendev.org/c/openstack/governance/+/820195

Unit tests job template is also updated to keep python
3.6 as a voting job.

- https://review.opendev.org/c/openstack/openstack-zuul-jobs/+/820286

This commit re-add the python 3.6 functional tests also which we
removed in https://review.opendev.org/c/openstack/nova/+/819194
also, re-adding py3.6/3.7 versions in setup.cfg classifier.

Change-Id: I7c83f1d64f31741dc51cc736265cf50fd0dad7af

.zuul.yaml

@@ -1,6 +1,34 @@
 # See https://docs.openstack.org/infra/manual/drivers.html#naming-with-zuul-v3
 # for job naming conventions.
 
+- job:
+    name: nova-tox-functional-centos8-py36
+    parent: openstack-tox-functional-py36
+    nodeset: devstack-single-node-centos-8
+    description: |
+      Run tox-based functional tests for the OpenStack Nova project
+      under cPython version 3.6 with Nova specific irrelevant-files list.
+      Uses tox with the ``functional-py36`` environment.
+
+      This job also provides a parent for other projects to run the nova
+      functional tests on their own changes.
+    required-projects:
+      # including nova here makes this job reusable by other projects
+      - openstack/nova
+      - openstack/placement
+    irrelevant-files: &functional-irrelevant-files
+      - ^.*\.rst$
+      - ^api-.*$
+      - ^doc/(source|test)/.*$
+      - ^nova/locale/.*$
+      - ^releasenotes/.*$
+    vars:
+      # explicitly stating the work dir makes this job reusable by other
+      # projects
+      zuul_work_dir: src/opendev.org/openstack/nova
+      bindep_profile: test py36
+    timeout: 3600
+
 - job:
     name: nova-tox-functional-py38
     parent: openstack-tox-functional-py38
@@ -15,12 +43,7 @@
       # including nova here makes this job reusable by other projects
       - openstack/nova
       - openstack/placement
-    irrelevant-files: &functional-irrelevant-files
-      - ^.*\.rst$
-      - ^api-.*$
-      - ^doc/(source|test)/.*$
-      - ^nova/locale/.*$
-      - ^releasenotes/.*$
+    irrelevant-files: *functional-irrelevant-files
     vars:
       # explicitly stating the work dir makes this job reusable by other
       # projects
@@ -515,6 +538,7 @@
         - nova-next
         - nova-tox-validate-backport:
             voting: false
+        - nova-tox-functional-centos8-py36
         - nova-tox-functional-py38
         - nova-tox-functional-py39
         - tempest-integrated-compute:
@@ -554,6 +578,7 @@
       jobs:
         - nova-live-migration
         - nova-live-migration-ceph
+        - nova-tox-functional-centos8-py36
         - nova-tox-functional-py38
         - nova-tox-functional-py39
         - nova-multi-cell

setup.cfg

@@ -20,6 +20,8 @@ classifiers =
     Operating System :: POSIX :: Linux
     Programming Language :: Python
     Programming Language :: Python :: 3
+    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