Fix publishing documentation

[Avasam]

Since the help files aren't shipped with the wheel in 307, the docs workflow fails.

Given the catch-22 nature of generating docs at the moment, and not wanting to create extra builds when not needed. I kept the PyPI download. But regerenate a .chm from source. (the help file generation honestly isn't that long anyway).

I also added doc generation as a CI test to sanity test that a PR won't break the docs publishing after a tag is created.

This PR makes the following changes:

• Generate a new .chm file in docs workflow since it's no longer shipped in wheels
• Pass the current python executable path to nmake instead of hardcoding a specific version
• Remove the redundant zip step, since https://github.com/actions/upload-artifact#upload-an-entire-directory already does it
• Update GitHub actions in docs workflow (also done in Bump GitHub actions and checkers #2376)
• PR validation that doc generation still works when changes are made in relevant files

There are no technical reasons preventing us from still shipping the help files (PyWin32.chm), other than maybe their size (see #1380 (comment)). If it's a long-term choice, then let's also remove the dead setup code to register them. (we could ship a web link file instead) Otherwise I can add it back to the wheel as part of the automated process. Either way that'll be a different PR.

This incidentally works towards #394

[Avasam]

If you still want this to be runnable w/o the python script, I think this should work to add a default executable location:

Suggested change

	HHC = hhc
	HHC = hhc
	# PYTHON is set in make.py, defaulting to the one found on PATH
	PYTHON = python

[Avasam]

Ah, another catch-22. py2d.py uses live introspection by importing modules. I feel like this should be feasible to resolve with static inspection APIs/AST, hacking around Python's import system, or just moving the docs job to depend on the self-install in CI.

[Avasam]

If we merged both workflows, we could push these as artifacts, then no need to download from PyPI

[Avasam]

I added this for the sake of testing in my PR, but if we keep this we wouldn't need to add a test in .github/workflows/main.yml

[mhammond]

Sorry for the delay, this is great, thanks!

[Avasam]

TODO: could we?

Open question on setuptools discussion: pypa/setuptools#4685