CI: do linkcheck on SPECS docs
Some of the specs are full of links to third party pages of tools and other resources. We need to make sure these links don't rot over time.
We check links with netlify: https://github.com/scientific-python/specs/blob/f3fad788a636b1a31957c6986f294e56b269beeb/netlify.toml#L6
ah, OK. Also from cron? E.g. I don't expect a link to not work at the time of adding it freshly in the PR.
No cron checks right now. Link checks are quite expensive, but we could do it once a week or so and file an issue. But I haven't set that up before, so hoping someone else is interested...
Oh, sure, I'm not suggesting more frequent checks than weekly/fortnightly.
I do have projects that run linkchecks, but all of those are either rely on jupyter-book or sphinx linkcheck functionality, but I'm sure someone have already found a linkcheck action that works reasonably well so we can just pull the config from an existing project.