Alert if website is down/not up-to-date.

[LukeMoll]

Since the website is hosted on Runciman, occasionally something falls over that means that the website goes down, or it doesn't update when a new commit is pushed to GitHub. This may go unnoticed for some time.

To make the Infrastructure team's lives easier, a simple "cron job" could be set up using GitHub Actions. This could check:

• That the website responds to HTTP requests
• That the Git commit SHA in the HTML comment at the start of the response matches the current HEAD of main. For an example, try View Source on any HackSoc.org page, or see git.jinja2.

Especially when this job is failing, email notifications could be spammy. For this reason, the job should not run too often (daily at most).

See also:
https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule