feat(action): do not depend on pipx in Nox action

[mayeut]

pipx is being re-added in actions/runner-images#9474

blocked by actions/runner-images#9256 (temp: don't use pipx commit)
blocked by actions/setup-python#808 (temp: python 3.8 & 3.9 missing on macos-14 commit)

[henryiii]

Do we know if pipx is going to be re-added? We could use this mechanism (both here and in cibuildwheel) until it is. And I wouldn't be shocked if 3.8 was never added to GHA macOS AS, Python didn't officially support AS at that point, it was very experimental. The 3.8 that ships on (at least previous versions of) macOS AS was an Apple patched fork. I'm not sure why 3.9 is missing though, as that had pretty solid support for AS.

[henryiii]

The matching PR was merged and released in cibuildwheel. @mayeut can we take this out of draft?

[mayeut]

I marked this PR as ready for review as requested by @henryiii

pipx is going to be re-added however this PR also deals with self-hosted runners on which pipx might not be available.
As for python 3.8/3.9, there's no timeline from upstream with issue/PR for a couple months.

[cjolowicz]

LGTM. Can we change the title to something like "do not depend on pipx in Nox action"?

[henryiii]

AFAICT pipx is just awaiting deployment. I'm not nearly as worried about not using pipx if it's available on all the official runners - a self hosted runner could just add pipx. Maybe we should just add the tests when pipx becomes available? What do others think? I'm fine either way.

[henryiii]

Suggested change

	shell: "${{ steps.localpython.outputs.python-path }} -u {0}"
	shell: "${{ steps.allpython.outputs.python-path }} -u {0}"

Not sure using the last activated one makes sense, but it’s what was done before. Seems like only activating 3.6 would be valid, but we must run from 3.7+, for example

[mayeut]

@henryiii, the last activated one is always 3.11:

nox/.github/action_helper.py

Lines 58 to 66 in efc17bb

	# we want to install python 3.11 last to ease nox set-up
	if "3.11" in cpython_versions_filtered:
	index = cpython_versions_filtered.index("3.11")
	index = versions.index(cpython_versions[index])
	cpython_nox = versions.pop(index)
	versions.append(cpython_nox)
	else:
	# add this to install nox
	versions.append("3.11")

[henryiii]

Couldn’t we use localpython?

[mayeut]

at some point, and that's probably still the case, setup-python was allowed to delete some python install to install a more specific one: e.g. you have the latest 3.11.y pre-installed, but specify 3.11.x in the nox action then, 3.11.y is deleted and localpython won't work anymore.

[henryiii]

Ah, makes sense. Should we bump to 3.12 now?