Add a release note about Python 3.11

This is now the only version of Python tested with Zuul.  Note that
change and also update the pypi classifiers.

That requires that we run all the nox jobs with Python 3.11, so they
are updated as well.

Change-Id: I9bb7514d5eab32fed814a5a054cc6be642e91ab4

.zuul.yaml

@@ -64,6 +64,8 @@
       test_setup_environment:
         ZUUL_TEST_ROOT: /tmp/zuul-test
         YARN_REGISTRY: "https://{{ zuul_site_mirror_fqdn }}:4443/registry.npmjs"
+      nox_force_python: "3.11"
+      python_version: "3.11"
 
 - job:
     name: zuul-nox-remote
@@ -82,6 +84,8 @@
         ZUUL_REMOTE_IPV4: "{{ nodepool.interface_ip }}"
         ZUUL_REMOTE_KEEP: "true"
         CI: "1"
+      nox_force_python: "3.11"
+      python_version: "3.11"
 
 - job:
     # Zuul cient uses this job so we can't just delete it yet.
@@ -114,8 +118,6 @@
     timeout: 7200  # 120 minutes
     vars:
       nox_keyword: tests
-      nox_force_python: "3.11"
-      python_version: "3.11"
 
 - job:
     name: zuul-nox-py311-multi-scheduler
@@ -336,7 +338,10 @@
     check:
       jobs:
         - zuul-build-image
-        - zuul-nox-docs
+        - zuul-nox-docs:
+            vars:
+              nox_force_python: "3.11"
+              python_version: "3.11"
         - nox-linters:
             vars:
               nox_install_bindep: false
@@ -367,7 +372,10 @@
     gate:
       jobs:
         - zuul-upload-image
-        - zuul-nox-docs
+        - zuul-nox-docs:
+            vars:
+              nox_force_python: "3.11"
+              python_version: "3.11"
         - nox-linters:
             vars:
               nox_install_bindep: false

releasenotes/notes/python-311-0766892d22cfba19.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Python 3.11 is now the only version of Python with which Zuul is
+    tested.

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = Zuul Team
 author_email = zuul-discuss@lists.zuul-ci.org
 home_page = https://zuul-ci.org/
-python_requires = >=3.8
+python_requires = >=3.11
 classifier =
     Intended Audience :: Information Technology
     Intended Audience :: System Administrators
@@ -14,9 +14,6 @@ classifier =
     Operating System :: POSIX :: Linux
     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 :: 3.11
 
 [pbr]