GH Actions: auto-cancel previous builds for same branch
GH Actions: auto-cancel previous builds for same branch

When the same branch is pushed again (and again), builds queues can start piling up.

The configuration now added, will auto-cancel any builds from previous pushes, whether already running or still waiting.

More than anything, this is a way to be kind to GitHub by not wasting resources which they so kindly provide to us for free.

Refs:
* https://github.blog/changelog/2021-04-19-github-actions-limit-workflow-run-or-job-concurrency/
* https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#concurrency

Brain-WP/BrainMonkey