Cannot push changes in GitHub Actions with custom user name and password

Next issue on my journey from Jenkins to GitHub.
I need to use a different user for pushing to work around branch restrictions. As such, I have used customUsername and customPassword parameters on Jenkins.

In GH actions, I replaced the password with the token (PAT). But this does not seem to work. I cannot find a way to tell the plugin to use a PAT instead of username/password...

Any ideas?

```
Pushing all to remote: origin
remote message: error: GH006: Protected branch update failed for refs/heads/main.
error: Changes must be made through a pull request.
```

When I removed the branch protection, just to test what this would change, I see the actual commit is done using the `runner` user, not my other technical user I had mentioned in customUsername. So, somehow, this feature does not work with PATs...