Feature Description

See https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency

This should allow for PRs not to queue up multiple jobs when multiple commits are pushed in a short time span. Should help reduce the slow queueing up of jobs we've been seeing.

Goal: on each PR, only allow a single job to run, on the latest-pushed commit. Cancel previous jobs if a newer commit has been pushed.

Note:

• do NOT enable this on devel, as we'd like to prove out every commit on that branch.
• The spell-checking workflow is already doing this