Option to exclude workflow initiator (GITHUB_ACTOR) as an approver

[timorthi]

Hi there, thanks for creating this GH Action - it's come in handy for some workflows over at @leaselock :)

We have a use case in which we want to allow a team of users to approve a step. However, if the user who initiates the workflow is also part of the team, we don't want to allow the initiator to self-approve.

This workflow initiator is exposed as a default environment variable GITHUB_ACTOR, so we added a small change to filter that user out.

I figured I'd share this PR as it might be useful for other users too. Perhaps we can toggle this behavior based on an input flag allow_workflow_initiator_as_approver: true|false?

[trstringer]

Thanks for your PR! I really like this, and agree this is a great feature to add. This should definitely be behind a configuration setting, like you mention. allow_workflow_initiator_as_approver is a little verbose, but I can't think of anything more accurate and shorter right now. Could you add that into the code, and have it default to true so that we don't break current users that rely on this behavior already?

Thanks again!

[timorthi]

@trstringer Updated! I've tested the input flag in a private repo and it works as expected. I went with kebab-case rather than snake_case to be consistent with the other inputs.

[trstringer]

Thank you for your contribution!!