Deprecate Parser.{config,env}

[AA-Turner]

It's unclear if these attributes are used in third-party projects, and removing them would allow for a great deal of simplification. I'm open to reversing this deprecation if the impact is too large.

A

[bsipocz]

This triggered in our CI for MyST-NB, I'm looking into the code now if we in fact use them or just inherited and propagated down the line.

https://github.com/executablebooks/MyST-NB/actions/workflows/tests_devdeps.yml

[bsipocz]

Indeed, we are using env in our parser class https://github.com/executablebooks/MyST-NB/blob/master/myst_nb/sphinx_.py#L56 as well as through the Myst-parser lib (https://github.com/executablebooks/MyST-Parser).

It's not trivially clear how difficult it would be to work around these deprecation, and to judge the impact, but I would say there are quite a lot of projects out there that uses MyST-NB for their rendering; a handful of them are listed here: https://executablebooks.org/en/latest/gallery/ but also some libraries such as scipy now relies of MyST-NB for their library documentation build: https://github.com/scipy/scipy/blob/main/pyproject.toml#L99