Script listing contributors should take into account Co-Authored information

The script we use for listing contributors of a product should take into account the Co-Authors information of a commit: this information is added automatically to commits whenever a pull requests is edited by multiple people on Github, and it might also be used manually by some of our tools.

See https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors for more details about github co-author syntax.