Drop python 3.9 and support python 3.13

Due to requirements repo dropped the constraints for
python3.9[1], Tempest needs to drop the python 3.9
support[2]. Because Tempest master cannot support
py3.9 anymore, it needs to be dropped from tempest
plugins also.

Also, add python 3.13 support which is tested as mandatory
in 2026.2 cycle.

[1] https://review.opendev.org/c/openstack/requirements/+/957587
[2] https://review.opendev.org/c/openstack/tempest/+/966101

Change-Id: I1c4f4b9890324bdcd3c06b8eda1afd8568589293
Signed-off-by: Ghanshyam Maan <gmaan@ghanshyammann.com>

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/trove/latest/
-python_requires = >= 3.9
+python_requires = >= 3.10
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -17,10 +17,10 @@ classifier =
     Programming Language :: Python :: Implementation :: CPython
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
     Programming Language :: Python :: 3.12
+    Programming Language :: Python :: 3.13
 
 [files]
 packages =