Migrate away from unmaintained twiggy

[gotmax23]

twiggy is apparently unmaintained upstream and has not had any commits in two years. We should switch to the builtin logging module or something else.

[felixfontein]

Considering that twiggy uses deprecated stdlib that has been reported in 2021, and a fix has been around since then as well, without any maintainer feedback to the issue or PR, I tend to agree.

Getting rid of it is more complex, though, since the code is used by both antsibull-core, and antsibull-docs and antsibull itself. I guess we need to do this in an antsibull-core 3.0.0 release, and antsibull-docs and antsibull must make a hard dependency bump (in new major releases, which is easy for antsibull but harder for antsibull-docs).

[gotmax23]

This is harder to replace, as I don't think logging has an equivalent to twiggy's .fields() API which we widely use. Still, I'd like to use the same approach as we did for sh: prepare to replace antsibull_core's logging API that uses twiggy in antsibull-core v2 and remove it in v3.

[felixfontein]

With 'remove it in v3', you mean 'change the API implementation to stop using twiggy, and use Python logging instead'?

[gotmax23]

Yeah, I guess. I don't think there's anything to prepare in antsibull-core v2 like we did for sh. We'd need to rewrite antsibull_core.logging and the logging configuration schemas, replace the calls to twiggy.dict_config in the antsibull-build and antsibull-docs CLI code, and handle any incompatibilities (e.g. calls to .fields()) all at the same time.

[felixfontein]

I tried a slightly different approach in #188.