Add support for Python 3.12

[hugovk]

The second Python 3.12 release candidate is out! 🚀

Call to action

We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.12 compatibilities during this phase, and where necessary publish Python 3.12 wheels on PyPI to be ready for the final release of 3.12.0.

Python 3.12.0 final is due out in two weeks: 2023-10-02.

---

Tested locally via tox:

❯ tox -e py312
py312: install_deps> python -I -m pip install attrs coverage pytest
.pkg: install_requires> python -I -m pip install 'setuptools>=40.8.0' wheel
.pkg: _optional_hooks> python /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: get_requires_for_build_sdist> python /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: get_requires_for_build_wheel> python /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: install_requires_for_build_wheel> python -I -m pip install wheel
.pkg: prepare_metadata_for_build_wheel> python /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
.pkg: build_sdist> python /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
py312: install_package> python -I -m pip install --force-reinstall --no-deps /private/tmp/client_python/.tox/.tmp/package/1/prometheus_client-0.17.1.tar.gz
py312: commands[0]> coverage run --parallel -m pytest
======================================================================================= test session starts ========================================================================================
platform darwin -- Python 3.12.0rc2, pytest-7.4.2, pluggy-1.3.0
cachedir: .tox/py312/.pytest_cache
rootdir: /private/tmp/client_python
collected 303 items

tests/test_asgi.py ssssssss                                                                                                                                                                  [  2%]
tests/test_core.py ...................................................................................................                                                                       [ 35%]
tests/test_exposition.py ..........................................................                                                                                                          [ 54%]
tests/test_gc_collector.py ..                                                                                                                                                                [ 55%]
tests/test_graphite_bridge.py .......                                                                                                                                                        [ 57%]
tests/test_multiprocess.py ..........................                                                                                                                                        [ 66%]
tests/test_parser.py ........................                                                                                                                                                [ 73%]
tests/test_platform_collector.py ..                                                                                                                                                          [ 74%]
tests/test_process_collector.py ....                                                                                                                                                         [ 75%]
tests/test_twisted.py s                                                                                                                                                                      [ 76%]
tests/test_wsgi.py .......                                                                                                                                                                   [ 78%]
tests/openmetrics/test_exposition.py ....................                                                                                                                                    [ 85%]
tests/openmetrics/test_parser.py .............................................                                                                                                               [100%]

================================================================================== 294 passed, 9 skipped in 5.26s ==================================================================================
.pkg: _exit> python /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  py312: OK (11.09=setup[4.66]+cmd[6.43] seconds)
  congratulations :) (11.17 seconds)

[csmarchbanks]

Thank you!

Similar to what you did for python 3.10, would you be willing to update setup.py and .circleci/config.yml as well? If not I can do that in a separate PR.

[hugovk]

Done, but it looks like CircleCI doesn't support Python 3.12 yet?

Starting container cimg/python:3.12
Warning: No authentication provided, using CircleCI credentials for pulls from Docker Hub.
  image cache not found on this host, downloading cimg/python:3.12

Error response from daemon: manifest for cimg/python:3.12 not found: manifest unknown: manifest unknown

[csmarchbanks]

Ah bummer, it does look that way. If it is ok I will leave this for a couple weeks until there is a 3.12 image and I can re-run the test then?

Since the tests all pass for you locally we shouldn't need to update anything at least!

[hugovk]

Fine by me to wait for the image :)

[csmarchbanks]

I reran the 3.12 test now that there is an image. Thanks!