Drop support for old Pythons; modernize & repair CI

[akx]

• The main change in this PR is to change the Python support level for the library to Python 3.8 and newer only. (Python 3.8, too, has been end-of-life for 2 weeks now, but it's still widely used, and readily available on GitHub Actions.)
  • It turns out that some of the test suite has been failing on Python 2 for a while now, but since it hasn't been in CI, no one knew. Presumably no one cares about Python 2 support for new versions of the library, either.
  • Python 3.6 and 3.7 will probably work, but Tox 4 doesn't support them, and Python 3.6 doesn't exist on GitHub Actions. python_requires could thus be '>=3.6', but we'd likely not know if it breaks.
• Secondly, it modernizes the Tox configuration that's used by the CI pipeline to use Tox 4, a split lint task (no need to lint on all versions...), and tox-gh for GitHub Python version determination.
• Finally, it fixes coverage reporting to happen again (via pytest-cov).

Since this changes the supported Python versions, I think this would be a semver-major change. I'm not sure if croniter is semver versioned.

Please see https://github.com/akx/croniter/pull/1 for the CI passing :)

[kiorky]

not ok for dropping support, we still support from python 2.6

[akx]

we still support from python 2.6

Yes, so far. As I said, this would be a semver-major version bump. Is there a reason to support Python 2.x going forward? Python 2.6 has been EOL for 10 years, Python 2.7 has been EOL for 4 years.

I can of course change this PR to not change the version requirements. However, looks like this package hasn't been CI tested on Python 2.7 since April 2023 and Python 2.6 since February 2020, so unless someone is manually testing on those versions of Python, there's really no guarantees. (As it is, testing locally on Python 2.7.18, there are 6 failing tests. I have no easy way of installing Python 2.6 on my machine.)

[kiorky]

Yes i know some project still use it from py2.

[akx]

Yes i know some project still use it from py2.

Okay. But those projects won't break if versions 4.0+ of croniter only support still-supported versions of Python.

In any case, see #94 for a PR that makes the current version's tests actually pass on Python 2.7 again.

[akx]

So @kiorky, should I just close this PR?

[kiorky]

I'm already taking bits of this PR to merge them by myself, a lot of thanks for all the ideas, though. I cant take it as is as i want to merge along things i had to do to modernize other things due for a long time, and this to be overall coherent. Look in the following days (i hope today, but not sure will have time to finish it :). If you still see some minor points that you want in, you can then rebase this PR, that's why i didn't closed it

In all cases, i'll poke you when done.

And again, really, thanks for the ideas and you will be quoted in next changelog as-is :) !

[kiorky]

• 3.0.4 is released with #97, quoting you as a major contributor of this release
• i manually merged everything i found cool in your PR.
• I 'm not willing to use tox-gh, so do no waste your time refreshing this PR with it.

Feel free to rebase / add something else you would find interresting.

Thanks !