Resource not accessible by integration - assigning author

I am using https://github.com/marketplace/actions/auto-author-assign
and my workflow is:

name: 'Auto Author Assign'
on:
  pull_request:
    types: [opened, reopened]
jobs:
  add-assignees:
    runs-on: ubuntu-latest
    steps:
      - name: auto-author-assign
        uses: toshimaru/auto-author-assign@v1.1.2
        with:
          repo-token: "${{ secrets.GITHUB_TOKEN }}"

When there is a new PR, the action fails to assign the PR to the person who sent it. See for example: https://github.com/drpaneas/romie/pull/58/checks?check_run_id=1220186720

the error says:

Run toshimaru/auto-author-assign@v1.1.2
  with:
    repo-token: ***
Error: Resource not accessible by integration

You need to use pull_request_target to allow forks to have access to the token.

Thanks for your reply. Does that mean I need to create a personal access token?
EDIT: I’ve found this page https://github.com/actions/checkout/blob/05aa1e5bb412bf00f60524f433ec33689f14e2e5/README.md#Checkout-pull-request-on-pull_request_target

No, a pull_request workflow from a fork won’t have access to the PAT secret either. A pull_request_target workflow does, and does get a GITHUB_TOKEN with write access. The idea is that the workflow for pull_request_target is already trusted code on the target branch, just make sure not to give any untrusted code from the pull request access to secrets or token.