Make Jazzy CI job required.

[sea-bass]

I just auto-merged a PR despite there being a failure in the Jazzy CI action.

Turns out this job is not marked as required in this repo.

@MatthijsBurgh can you set this up?

[MatthijsBurgh]

Jazzy is now required. Please fix the CI before making any other changes to this repo.

[sea-bass]

Thanks! It seemed to have been a flaky testz but I will keep a look out.