triggering equipment tests

[emiltin]

Previously, adding the label 'equipment' would trigger test on equipment connected to the test hub.

But issues related to bugs in equipment was also using this label. To avoid confusion, the label 'testhub' is now used to trigger testing on equipment.

The workflow has also been changed to support retesting each time a commit is added. But since reading the current labels is not straightforward in the workflow file, the label when the PR was created is used. What this means is that if you add the 'testhub' label after the PR was created, you might need to close and reopen then PR.

The worflow triggers on:
pull_request:
types: [ opened, reopened, synchronize, labeled ]

And the step has the filter:
if: ${{ github.event_name == 'schedule' || contains(github.event.pull_request.labels.*.name, 'testhub') }}

So if you open, reopen, commit or add a label, the workflow is triggered. But the actual test step is skipped unless it the trigger was a schedule, or the label 'test'hub' was set when the PR was opened or reopened.