ci chore: safari tests are failing

[Lee Read]

Version
Current master

Platform
Operating System: macos
Browser vendor: safari

Symptom
On GitHub Actions, Safari tests fail on first navigation to our test page.
Tests pass locally on a macOS.

Diagnosis
After some poking about, I think this might be Safari no longer having local file access enabled.
I think this means our file:/ urls won't work.

Enabling local file access is easily enough done interactively through Safari Developer settings, but not documented nor straightforward how it might be achieved programmatically from the terminal.
And it may not even be the solution.

After some trial and error, I think it will be easier to fire up a static web server to server our test pages and then access them via http:/ urls.

Action
I'll try out the web server approach and see if that works.