How to get the email of the last author of a commit on a PR?

I’m currently only triggering workflow runs on Pull Requests:

on:
  pull_request:
    types: [assigned, opened, synchronize, reopened, ready_for_review, unlocked]

I need the email address of the author of the commits of my pull request event. Also, since I don’t have “pusher” here, ${{github.event.pusher.email}} doesn’t exist.