MAINT: move static metadata to pyproject.toml

[mwtoews]

This PR is a follow-up from #2419, and moves the project metatdata from setup.py to pyproject.toml as described by PEP 621 and supported by setuptools >= 61. This supersedes #2424 as there are more community commitments behind maintaining project metadata in pyproject.toml than setup.cfg.

Details:

• Add new metadata: keywords and classifiers.
• Change author to "Kelsey Jordahl" (with existing email match), move "GeoPandas contributors" as maintainers.
• Change licence from slightly ambiguous "BSD" to SPDX compliant "BSD 3-Clause".
• Change how packages are found, using patterns geopandas and geopandas.*. This now finds geopandas.io.tests, which seems to be unintentionally excluded.
• Change how package data is found, using an explicit list of datasets.
• Option install_requires is moved to pyproject.toml as dependencies. If a workaround is indeed required for ReadTheDocs, a modern approach should be found.
• Most of setup.py is used to support versioneer or anyone that expects to see this file. For POSIX systems, it is now an executable, and runs python3.

Some of these are new or changed, so feedback or suggestions are welcome.

[martinfleis]

This looks okay to me. Thanks!

[jorisvandenbossche]

Given the experimental status for this feature in setuptools (and the problems we have seen in pyproj/shapely for debian packagers), let's maybe wait a few more months with this? (I think it's OK to just leave open the PR)

[mwtoews]

I've checked this with a few debian docker images, and not surprisingly, it does not build with testing (bookworm), which uses a slightly older setuptools. But it does work with debian unstable (sid), which is encouraging.

Agree to hold off a merge until I can see a clean check with debian testing.

[EwoutH]

Given the experimental status for this feature in setuptools

Just a heads up: setuptools declared defining metadata in pyproject.toml to be stable in June.

[jorisvandenbossche]

That's only for the general project metadata, though, the [tool.setuptools] table is still "beta".

(and anyway, whatever setuptools says about it doesn't change potential downstream packaging problems if they don't yet support such recent setuptools)

[mwtoews]

Good news, setuptools in debian testing was recently upgraded and I've checked this with a docker image of bookworm (debian testing) with success. I can resolve the conflicts if there is appetite to merge this.

[martinfleis]

@mwtoews great! Let's resolve the conflicts and merge then!

[martinfleis]

Thanks @mwtoews!

[Zeroto521]

Hi, since 0.26, versioneer has started to support pyproject.toml file.
I thought we could move [versioneer] section from setup.cfg into pyproject.toml.

[martinfleis]

We could do the same with pytest but flake8 does not currently support pyproject.toml (PyCQA/flake8#234), so we won't be able to get rid of setup.cfg anyway.