This adds a concurrency section to all github workflows to cancel any
in progress workflow when a branch is updated. This should cancel any
ongoing or queued workflows, e.g. when a pull request is updated.
Signed-off-by: David Lechner <david@pybricks.com>
The existing actions/checkout@v2 is causing Node v12 deprecation warnings
to be shown in GitHub Actions. v3 uses Node v16, which will stop the
warnings.
