Exclude GitHub links from link checker

[georgp23]

Added exclusion rules for GitHub links in the docs-test session to prevent Sphinx linkchecker from flagging these links. This change updates the noxfile.py to include a list of excluded URLs

[willingc]

Hi @georgp23. Thanks for the PR. I'm curious. Why do you recommend excluding GitHub from the linkchecks in the noxfile? Are you seeing link failures?

[willingc]

Related to #442

[lwasser]

Hey there @georgp23 thank you for your time in submitting this PR.

Where did you find pyOpenSci / this issue?

Related to this PR, if you look at where CI is actually failing, it's not in the nox step, rather it's html proofer. which means we'd need to fix the pre-commit config settings for html proofer to skip any url's that have github.com in them.

So this PR is well intentioned but it's not actually addressing the CI point of failure that we need to address.

Another tip!! When you open a PR related to an issue, it's a great idea to start by commenting on the issue to discuss with the team that you wish to contribute! then, you can submit a pr and reference the issue in your pr!!

ALternatively we could use lychee like we are using in the website repository - our approach to this fix, would be better served discussing in the open issue rather than here. So it could make sense to either close this and start again or update it with a better fix after discussing in the issue the best approach.

hopefully that is helpful. Looking forward to hearing from you.