GitHub workflows have now a feature in beta, concurrency. One can read more in here: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency

The feature enables to stop an already running workflow when a new one is enqueued. Enabling this would save lots of time on CI servers for jobs that are already obsolete.
To configure it, this should be added to the continuous integration yml file:

concurrency:
  group: ci-${{ github.ref }}
  cancel-in-progress: true

@djspiewak Would you consider adding this feature even though is still in Beta on GitHub side? I would be willing to contribute it.