setuptools bdist_wheel.universal is deprecated, removal expected 2025-08-30

[moreati]

Using python -m build to create a mitogen wheel results in several warnings, most critically that universal (i.e. Python 2 + Python 3) wheel support is due to end in a 2 months

!!

        ********************************************************************************
        With Python 2.7 end-of-life, support for building universal wheels
        (i.e., wheels that support both Python 2 and Python 3)
        is being obviated.
        Please discontinue using this option, or if you still need it,
        file an issue with pypa/setuptools describing your use case.

        By 2025-Aug-30, you need to update your project and remove deprecated calls
        or your builds will no longer be supported.
        ********************************************************************************

!!

Mitogen currently relies on this.

mitogen-build.log

TODO

• Is deprecation only within setuptools? Or will e.g. twine, pypi.org also reject universal wheels?

[moreati]

Some discussion of alternatives in pypa/setuptools#4617, pypa/setuptools#4939. Other options

• build 2 wheels per release
• drop Python 2.x support

[webknjaz]

Other options

* build 2 wheels per release

You don't really need this. The only thing universal = 1 does is tagging wheels with py2.py3. That's it. It literally does not do anything else. For as long as you set it through the non-deprecated configuration option (i.e. python_tag = py2.py3), it'll keep working the same.

drop Python 2.x support

If you go for this, remember to pair the change with updating python_requires and the trove classifiers in setup.py.

[webknjaz]

Made a drive-by PR: #1286