[Feat]: define output variables

[AndreasAugustin]

Describe the feature

currently the action does not have any github action outputs.

Please add output variable pr_branch_name

Use Case

some use cases require outputs (e.g. discussion #467 )

Proposed Solution

https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-output-parameter

Acknowledgements

• I may be able to implement this feature request