Update gate jobs as per the 2023.1 cycle testing runtime

As per 2023.1 testing runtime[1], we need to test on Ubuntu
Jammy (which will be taken care by tempest and devstack patches
to move base jobs to Jammy) and at least single job to run on
Ubutnu Focal (for smooth upgrade). Also, python 3.10 testing is
voting now.

This commit makes python 3.10 functional job as voting and python 3.10
unit test job are voting via generic template. Python 3.8/3.9 jobs are
running on Focal and python 3.10 on Jammy.

[1] https://governance.openstack.org/tc/reference/runtimes/2023.1.html

Change-Id: I97b82399af9a640353ba979965c202afcb224163

.zuul.yaml

@@ -16,7 +16,6 @@
         - openstack-tox-functional-py310:
             required-projects:
               - openstack/placement
-            voting: False
     gate:
       jobs:
         - openstack-tox-functional-py38:
@@ -28,5 +27,3 @@
         - openstack-tox-functional-py310:
             required-projects:
               - openstack/placement
-            voting: False
-

setup.cfg

@@ -19,6 +19,7 @@ classifier =
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
 
 [files]
 packages =

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 3.18.0
-envlist = py39,functional,pep8
+envlist = py3,functional,pep8
 skipsdist = true
 # Automatic envs (pyXX) will use the python version appropriate to that
 # env and ignore basepython inherited from [testenv]. That's what we