Add openstack-tox-py311 job

Some projects want to include python3.11 in their testing, provide a
generic job for that like we have for older python versions.

Change-Id: I725b94bee6601a81b5e64db204bf3488674eff9d

zuul.d/jobs.yaml

@@ -451,6 +451,23 @@
 
       Uses tox with the ``py310`` environment in arm64 platform.
 
+- job:
+    name: openstack-tox-py311
+    parent: openstack-tox
+    nodeset: debian-bookworm
+    timeout: 2400
+    description: |
+
+      Run unit tests for an OpenStack Python project under cPython
+      version 3.11.
+
+      Uses tox with the ``py311`` environment.
+    irrelevant-files: *common-irrelevant-files
+    vars:
+      tox_envlist: py311
+      bindep_profile: test py311
+      python_version: '3.11'
+
 - job:
     name: openstack-tox-pypy
     parent: openstack-tox