build: fix metainfo

[e-kwsm]

---

Please use a simple string containing a SPDX expression for project.license. You can also use project.license-files. (Both options available on setuptools>=77.0.0).

By 2027-Feb-18, you need to update your project and remove deprecated calls
or your builds will no longer be supported.

See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.

---

---

Usage of dash-separated 'description-file' will not be supported in future
versions. Please use the underscore name 'description_file' instead.

Available configuration options are listed in:
https://setuptools.pypa.io/en/latest/userguide/declarative_config.html

This deprecation is overdue, please update your project and remove deprecated
calls to avoid build errors in the future.

See pypa/setuptools#5011 for details.

---

---

Please consider removing the following classifiers in favor of a SPDX license expression:

License :: OSI Approved :: GNU General Public License v3 (GPLv3)

See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.

---

[ZedThree]

Thanks @e-kwsm! I think we could also just do away with setup.cfg completely too. Would you mind also moving any remaining config into pyproject.toml?

[ZedThree]

Lovely, thanks @e-kwsm!

[e-kwsm]

markdown-include/setup.cfg

Line 2 in 8da79f0

description-file = README.rst

README.rst is gone and

markdown-include/pyproject.toml

Line 11 in 8da79f0

readme = "README.md"

is valid, so I just removed the file.

[e-kwsm]

Hmm, this seems to require setuptools>=76.0.

[ZedThree]

Bah, this is failing on py3.8. I'm not sure if this change also requires us to drop support for 3.8. I would guess that it's due to using an older setuptools, but it looks like it's failing when parsing pyproject.toml, so it might not even be possible to specify a new version of setuptools?

We should at least bump the required setuptools version to 77.0