Replace markdown-link-checker with Linkspector

[alexdewar]

I was looking at adding a link checker to another project and thought it would be worth checking out linkspector as an alternative to the existing markdown-link-checker action we're using now. The project's by the same author and on the markdown-link-checker repo it suggests using linkspector instead.

I thought the blog would be a good place to try it out because it contains a bunch of links.

Linkspector a couple of advantages over markdown-link-checker:

1. It uses a headless version of Chrome to resolve the links, so the rate of false positives (i.e. good links failing) should be much lower
2. It comments on your PR on the line where the failing link is, which is handy

I'm currently using the ubuntu-22.04 runner cf. ubuntu-latest as there's an open bug affecting the latter. Looks like there's a fix in the works though.

[AdrianDAlessandro]

I'm not convinced it's working. I would still expect it to fail on the websites that have a CAPTCHA test and it's not failing.

Can you put in a link that we know for sure is broken?

[github-actions]

🚫 [linkspector] _{reported by reviewdog 🐶}
Cannot reach https://github.com/ImperialCollegeLondon/madeup_link. Status: 404

[alexdewar]

@AdrianDAlessandro I added a broken link just to double-check it's working ^^

[AdrianDAlessandro]

Wonderful! Seems good to me! I guess you can revert that commit now

[dc2917]

I wondered whether fail_on_error meant that as soon as it found a broken link, it stopped reporting (thus not finding further broken links), so looked it up and apparently this option is deprecated (link)

[alexdewar]

Good spot!

[AdrianDAlessandro]

Are you going to implement this elsewhere / in the python template?

[alexdewar]

I was thinking of changing my projects to use it. That's a good shout about the Python template -- I guess we're going to be using that for the foreseeable future.