setup.cfg: add `metadata.project_urls`

[generalmimon]

Fix https://github.com/kaitai-io/kaitai_struct_python_runtime/issues/69

According to a project example https://pypi.org/project/PyScaffold/4.3/ + https://github.com/pyscaffold/pyscaffold/blob/v4.3/setup.cfg#L7-L15, the "Homepage" link pulled from metadata.url apparently stays even if I add project_urls, so all links at PyPI resulting from this change should be (I'm not sure about their order, but again links on https://pypi.org/project/PyScaffold/4.3/ seem to be sorted alphabetically except the implicit "Homepage" link at the beginning):

• Homepage
• Documentation
• Gitter
• Source
• Tracker

Currently (see https://pypi.org/project/kaitaistruct/0.10/) the project links are just:

• Homepage

[KOLANICH]

IMHO it'd be a bit redundant to add the links source code and issue tracker since everyone knows that source code hostings (GitHub currently) are used for that. So IMHO 1 homepage link to this repo is enough. The links to the docs ... you don't have to limit oneself. Proposal: 1 link to the docs for python runtime, and another one to the guide to KS language.

[KOLANICH]

Also: setup.cfg is deprecated, convert it to pyproject.toml using ini2toml tool.

[dgelessus]

Also: setup.cfg is deprecated,

From where do you have that information? The setuptools docs for setup.cfg don't mention anything about it being deprecated. All I can find is pypa/setuptools/milestone/7 about eventually deprecating setup.cfg, but that hasn't happened yet. The setuptools maintainers also mentioned in multiple places that the deprecation period would probably be "forever", so there's no rush.

convert it to pyproject.toml using ini2toml tool.

That's still not an option. As before, pyproject.toml-based configuration requires setuptools 61.0.0, which requires Python 3.7, and we still supports version before that.

In any case, switching to a different configuration format is off-topic for this PR.

[generalmimon]

@dgelessus:

The list of links looks good to me. I personally wouldn't have added a Twitter link here (I think it's not all that relevant when coming from PyPI)

I agree that it's not that relevant for the Python runtime, and it's not clear what a Python user would find there.

[generalmimon]

@dgelessus:

A link to the docs sounds good, but I have no strong opinion about linking to the main docs or the Python notes (the reader can always click through to the other docs if needed).

That's true, so I think the main docs are fine.