Add URLs to linkcheck_ignore

[cbrnr]

The following URL caused the link checking to fail, so I added them to linkcheck_ignore:

• r"https://math-atlas\.sourceforge\.net/?": 403 error
• r"https://click\.palletsprojects\.com/.*": self-signed certificate error
• r"https://typer\.tiangolo\.com/.*": self-signed certificate error

This URL caused an anchor not found error:

• r"https://docs\.github\.com/"

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📚 Documentation preview 📚: https://python-packaging-user-guide--1881.org.readthedocs.build/en/1881/

[cbrnr]

Any idea why the linkcheck fails? I don't see any log entries...

[cbrnr]

OK, I think I've fixed all errors...

[woodruffw]

Thanks @cbrnr, this LGTM (and would unblock other docs PRs).

CC @webknjaz @ncoghlan as editors 🙂

[webknjaz]

Why does this have so many unrelated changes? Is it possible to make the diff small?

[woodruffw]

It looks like @cbrnr went ahead and fixed some of the other URLs too (which were probably over-matching due to . being interpreted in regexes). I don't have a strong opinion on whether those changes should be included or not though.

[cbrnr]

Exactly, the linkcheck_ignore items are all regexes, and previously dots were not escaped (so matched any character). This is usually not really a problem in practice, but I thought while I'm at it I might as well fix all entries.

[webknjaz]

I tend to prefer atomic PRs. The title says it fixes one single URL but what I see in the diff is a bunch of other URLs with zero justification. Plus refactoring. Maybe something I missed in between these too.

[ncoghlan]

Thanks for simplifying the PR (and aligning the title with the content). LGTM, so I'm going to merge and unblock the other PRs affected by the link check failures.