Workflow fails to send Slack message if API is unavailable.

See https://github.com/seqeralabs/showcase-automation/actions/runs/7435459503/job/20230838609 for an example.

If the API is unavailable, the workflow fails and never reports it. We could add a hook for saying 'thing is late', or we could just wait. Given we can use a heartbeat monitor for uptime, we should probably wait.