Add support for py39

- Use version agnostic "py" inside tox default envs
- Enable py39 testing jobs (new template contains them)
- Address deprecation warning in setup.cfg regarding use of dashes
  instead of underlines (avoid future breakage with setuptools)

Change-Id: I26be50e029393e01db6718a21ac67d669ccd2e0c

setup.cfg

@@ -1,12 +1,12 @@
 [metadata]
 name = tripleo-heat-templates
 summary = Heat templates for deploying OpenStack with OpenStack.
-description-file =
+description_file =
     README.rst
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 license = Apache License (2.0)
-home-page = https://opendev.org/openstack/tripleo-heat-templates
+home_page = https://opendev.org/openstack/tripleo-heat-templates
 classifier =
     Environment :: OpenStack
     Development Status :: 3 - Alpha

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 minversion = 2.0
 skipsdist = True
-envlist = pep8,py37,tht
+envlist = pep8,py,tht
 
 [testenv]
 basepython = python3

zuul.d/layout.yaml

@@ -5,7 +5,7 @@
       - check-requirements
       - release-notes-jobs-python3
       - tripleo-standalone-scenarios-pipeline
-      - openstack-python3-victoria-jobs
+      - openstack-python3-wallaby-jobs
       - tripleo-standalone-multinode-ipa-pipeline
       - tripleo-upgrades-master-pipeline
     check: