Use action without additional checkout

[WtfJoke]

Its not needed to checkout the actions repo using actions/checkout in order to run the action. Instead the action can be run directly using the uses expression: github/actions-oidc-debugger@main.

It would be better to stick to moving tags like v1 (but v1 seems to be not moving, thats why I stick to main branch instead) like described here in Action Versioning.