Moves supported python runtimes from version 3.8 to 3.10

Within 2023.2 python version 3.9 and 3.10 are the
supported python runtimes [1].
[1] https: //review.opendev.org/c/openstack/governance/+/872232

Change-Id: I09eff64e3701f1f8f63fd931e8053d1ca1c10a4c

.zuul.yaml

@@ -2,7 +2,7 @@
     templates:
       - check-requirements
       - lib-forward-testing-python3
-      - openstack-python3-antelope-jobs
+      - openstack-python3-jobs
       - periodic-stable-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3

setup.cfg

@@ -6,7 +6,7 @@ summary = Oslo Metrics API
 description_file =
     README.rst
 home_page = https://opendev.org/openstack/oslo.metrics
-python_requires = >=3.8
+python_requires = >=3.9
 classifier =
     Environment :: OpenStack
     Intended Audience :: Developers
@@ -15,8 +15,8 @@ classifier =
     Operating System :: OS Independent
     Programming Language :: Python
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: Implementation :: CPython