CI: test on 3.12

[twoertwein]

• Closes python 3.12 and pyright 1.1.334 error: Method "fromtimestamp" overrides class "datetime" in an incompatible manner #813 (Replace xxxx with the Github issue number)
• Tests added: Please use assert_type() to assert the type of any return value

poe pytest (circular import error) fails for me but pytest tests works?! Let's see what happens on the CI.

[twoertwein]

Unrelated: could replace isort and black with ruff (pandas might replace black with ruff pandas-dev/pandas#56554)

[Dr-Irv]

When I look into the Actions on github, it shows that the CI is failing.

But I also don't understand why the jobs aren't showing up in the Conversation tab.

[Dr-Irv]

One suggestion to help with maintenance. Convert out of draft if you're happy with it.

[Dr-Irv]

Given that this pattern is appearing all over the place, and hopefully we can one day remove it, it might be better to just create a special item in tests/__init__.py that returns

 pytest_warns_bounded(
        DeprecationWarning,
        match="datetime.datetime.utcnow",
        lower="3.11.99",
        version_str=platform.python_version(),
    )

Then we know there is one place that is catching the same warning.

[twoertwein]

I found a nicer solution :) pytest_warns_bounded is used in only one place now, so I don't think creating a new function for it would make sense anymore.

[Dr-Irv]

Thanks @twoertwein . I like the idea of using pyproject.toml and [tool.pytest.ini_options] to handle the dateutil issue.