Dry run mode

[FriedrichFroebel]

I recently discovered this action and considered using it in my own projects.

For now, it seems to always generate a pull request if there are changes. While this is perfectly fine for most use cases, I would like to use this as a check only, id est an action which reports the corresponding action versions to update inside each workflow and fails if there are updates, without creating a corresponding pull request.

With the current updater class, this seems to be tricky: I would either have to subclass this in some code of mine and overwrite the complete run method - or monkey-patch at least create_pull_request.

Is there any chance of providing some sort of "dry run" mode natively, which just performs the check instead of sending a pull request as well?