Feature Request: Add the option to add labels to the created PR

[xiehan]

This seems like a fairly standard practice for GitHub Actions that create issues and PRs for you so I was surprised to find this wasn't an option here. We've got a couple of very PR-heavy repos so being able to add labels like "automated" and "dependencies" is very helpful for filtering bot-generated PRs from ones created by humans, especially for reminders and notifications.