Support reusable workflows

[tdsmith]

Reusable workflows are a new feature [1] that allow a workflow to be dispatched from another workflow.

Using reusable workflows involves creating a job with a uses key and no steps key [2].

This change allows these jobs to pass silently through actions-includes instead of causing a failure.

[1] https://github.blog/2021-11-29-github-actions-reusable-workflows-is-generally-available/ [2] https://docs.github.com/en/actions/learn-github-actions/reusing-workflows#calling-a-reusable-workflow

[tdsmith]

Thanks! Happy to test this; is a doctest on the changed functions what you're looking for or is there something else that would be useful? I couldn't immediately figure out how the files in /tests are used.