Enable py39 testing with hacking

- bump template to wallaby to make use of py39 job
- advertise py39 support in metadata
- clean default tox envlist to be python version agnostic

Change-Id: I47ce403f35460bcf27d044450c7e6ed00cda7c4f

.zuul.yaml

@@ -3,7 +3,7 @@
       - publish-openstack-docs-pti
       - openstack-cover-jobs
       - openstack-python35-jobs
-      - openstack-python3-victoria-jobs
+      - openstack-python3-wallaby-jobs
       - release-notes-jobs-python3
     check:
       jobs:

setup.cfg

@@ -26,6 +26,7 @@ classifier =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
 
 [files]
 packages =

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 minversion = 3.18.0
 skipsdist = True
-envlist = py36,py38,pep8,pypy
+envlist = py,pep8
 ignore_basepython_conflict = True
 
 [testenv]