Conditional logic for deployment commit messages isn't working

When GitHub Actions deploys to GitHub Pages, it uses conditional logic to decide which commit message to use. According to the config file, it looks like the commit message should be determined by the event that triggered the build:

https://github.com/alphagov/govuk-developer-docs/blob/b0c0a6d958b82af36184794e5e9eaf5559262252/.github/workflows/ci.yml#L31-L38

However in practice, the commit message is always "Hourly scheduled redeploy".

It looks like ${{ github.event.number }} always evaluates to an empty string. This seems consistent with the GitHub docs for builds triggered by a 'push' event, which suggests that number isn't a property of 'push' events.

Instead, I think we could probably change the if statement to something like this:

- if [ "${{ github.event.number }}" == "" ]; then
+ if [ "${{ github.event_name }}" == "schedule" ]; then

It assumes that cron-triggered builds have an event_name of "schedule" – which I think is correct, but this assumption would need to be tested.

Start in .github/workflows/ci.yml around lines 31-38, then check the GitHub Actions event context for schedule and push triggers. Test the workflow's conditional logic for both trigger types and confirm that deployed commit messages use the event-specific message instead of always using "Hourly scheduled redeploy".