Remove Python 3.8 support

Python 3.8 is no longer part of the tested runtimes for 2024.2[1]
because its EOL is coming soon.

Also update the python versions in functional jobs to reflect
the supported versions.

[1] https://governance.openstack.org/tc/reference/runtimes/2024.2.html

Change-Id: I316119d1b9a3e8aad75c764e5a6d64a6e7069bcb

.zuul.yaml

@@ -9,12 +9,13 @@
       - release-notes-jobs-python3
     check:
       jobs:
-        - openstack-tox-functional-py38
+        - openstack-tox-functional-py39
+        - openstack-tox-functional-py312
         - tempest-smoke-py3-osprofiler-redis
         - tempest-smoke-py3-osprofiler-sqlalchemy
     gate:
       jobs:
-        - openstack-tox-functional-py38
+        - openstack-tox-functional-py39
 
 - job:
     name: tempest-smoke-py3-osprofiler-redis

releasenotes/notes/remove-py38-e2c2723282ebbf9f.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Support for Python 3.8 has been removed. Now the minimum python version
+    supported is 3.9 .

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/osprofiler/latest/
-python_requires = >=3.8
+python_requires = >=3.9
 classifier =
     Environment :: OpenStack
     Intended Audience :: Developers
@@ -15,10 +15,10 @@ 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
+    Programming Language :: Python :: 3.12
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: Implementation :: CPython