Switch to 2023.2 testing runtime py version

We have prepared general testing template now and
that has been updated for 2023.2 (current dev cycle)
testing runtime.
- https://review.opendev.org/c/openstack/openstack-zuul-jobs/+/873051

Switching election repo testing to the general template
and we do not need to update it in future cycle (all adjustment
of future cycle testing runtime will be handled by central place).

Also, remove basepython to avoid cnoflcit in py version env.

Change-Id: I3ab844e6727519e5a62401b44166e41d8d7a2582

.zuul.yaml

@@ -1,9 +1,3 @@
 - project:
     templates:
-      - openstack-python36-jobs
-    check:
-      jobs:
-        - openstack-tox-pep8
-    gate:
-      jobs:
-        - openstack-tox-pep8
+      - openstack-python3-jobs

setup.cfg

@@ -15,7 +15,8 @@ classifier =
     Programming Language :: Python :: Implementation :: CPython
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
 
 [files]
 packages =

tox.ini

@@ -1,9 +1,8 @@
 [tox]
 minversion = 2.0
-envlist = py36,pep8
+envlist = py3,pep8
 
 [testenv]
-basepython = python3
 usedevelop = True
 deps =
   -r{toxinidir}/requirements.txt