Update python versions for testing

Given the supported python runtimes for 2025.2 (Flamingo) [0]:
- modify .zuul.yaml to run the functional jobs in py310 and py312
  (py311 testing is not required)
- update tox.ini to support unit and funcitonal tests for:
  * python3 (default system python3)
  * python3.10 (minimum supported)
  * python3.11 (supported)
  * python3.12 (maximum supported)
  * python3.13 (will be default in Debian 13 before Flamingo release)

The zuul, tox config in stable branches are unchanged.

[0] https://governance.openstack.org/tc/reference/runtimes/2025.2.html

Change-Id: Ida26296f0bf95474f889473410179044a930ee86

.zuul.yaml

@@ -14,7 +14,7 @@
         - cinder-mypy
         - cinder-tox-bandit-baseline:
             voting: false
-        - openstack-tox-functional-py39:
+        - openstack-tox-functional-py310:
             irrelevant-files: &functional-irrelevant-files
               - ^.*\.rst$
               - ^cinder/locale/.*$
@@ -23,7 +23,7 @@
               - ^doc/.*$
               - ^releasenotes/.*$
               - ^reno.yaml$
-        - openstack-tox-functional-py311:
+        - openstack-tox-functional-py312:
             irrelevant-files: *functional-irrelevant-files
         - cinder-rally-task:
             voting: false

tox.ini

@@ -42,7 +42,7 @@ passenv =
   *_proxy
   *_PROXY
 
-[testenv:py{3,38,39,310,311,312}]
+[testenv:py{3,310,311,312,313}]
 # NOTE: Do not move the constraints from the install_command into deps, as that
 #       may result in tox using unconstrained/untested dependencies.
 #       We use "usedevelop = True" for tox jobs (except bindep), so tox does 2
@@ -62,7 +62,7 @@ install_command = {[testenv:py3]install_command}
 setenv =
   OS_TEST_PATH = ./cinder/tests/functional
 
-[testenv:functional-py{3,38,39,310,311,312}]
+[testenv:functional-py{3,310,311,312,313}]
 install_command = {[testenv:functional]install_command}
 setenv =
   {[testenv:functional]setenv}