> Did I do something wrong or do you need to allow me to push?

Yes, I've added you to the collaborators on my fork (lulouie/cpython).

But in fact, new GitHub workflow will need to do something different, not just edit-and-commit. You will need to go to PR 1382 (https://github.com/python/cpython/pull/1382) and start a new review. Click "file changes", when your cursor hovers on the source code line, it will pop out a blue plus icon on the line number, then click it to add a new comment on it, after that, click "start review" and do the rest comment.

After comment finish (maybe multiple lines), the top nav bar has a green button "Review changes" with total comment count, click it and add the summary comment for this review, and choose this is a comment, approve, or requests changes. In this case, you will choose requests changes for it. Also, Python member's requests changes will block the merge process, until all requests changes were approval.

In summary, in GitHub workflow, code review will be like a request, and the main committer stays for who create this PR, not reviewers.