Remove Python 3.9 support

Python 3.9 was removed from the tested runtimes for 2025.2[1] and has
not been tested since then.

Also add Python 3.13 which is part of the tested runtimes for 2025.2.
Now unit tests job with Python 3.13 is voting.

Also bump flake8-import-order to 0.19.2, which replaces
the pkg_resources dependency with importlib.metadata. This allows
the pep8 job to run on modern setuptools and Python 3.12.

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

Change-Id: I91353194e57976cd5fed0f72a841de9fe2a899ea
Signed-off-by: Riccardo Pittau <elfosardo@gmail.com>

releasenotes/notes/remove-py39-7216a052c6029aa9.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Support for Python 3.9 has been removed. Now the minimum python version
+    supported is 3.10 .

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/virtualbmc/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 =

tox.ini

@@ -29,7 +29,7 @@ passenv =
 [testenv:pep8]
 deps=
     hacking~=6.1.0 # Apache-2.0
-    flake8-import-order~=0.18.0 # LGPLv3
+    flake8-import-order~=0.19.2 # LGPLv3
     pycodestyle>=2.0.0,<3.0.0 # MIT
     doc8~=1.1.0 # Apache-2.0
 commands =
@@ -84,4 +84,4 @@ deps = codespell
 # note(JayF): {posargs} lets us run `tox -ecodespell -- -w` to get codespell
 #             to correct spelling issues in our code it's aware of.
 commands =
-  codespell {posargs}
+  codespell {posargs}