Use github.token to comment on PR when running workflow on pull_request from fork

I am trying to report some information to pull_request comments using token provided by GitHub Actions. Workflow is triggered by pull_request synchronize event. Head branch comes from fork

      curl -fsSL ${{github.event.pull_request.comments_url}} \
        -X POST \
        -d "{\"body\"::\"markdown_comment_body\"}" \
        -H "Accept: application/vnd.github.v3+json" \
        -H "Authorization: token ${{github.token}}"

The error message is:

curl: (22) The requested URL returned error: 403

And this works fine when PR is from the same repository (non-fork)