[Schema Inaccuracy] `/repos/{owner}/{repo}/pulls/comments/{comment_id}` actually has nullable `user`

[bigfootjon]

Schema Inaccuracy

Pull Requests comments claim to have a non-nullable user (the field is marked as "required") yet this field is actually nullable.

Expected

The field user should not be marked as required.

Reproduction Steps

/repos/ocaml/ocaml/pulls/comments/1758736814 which has:

...
  "user": null,
...

[github-actions]

[This is an automated message] This issue may have been opened accidentally. I'm going to close it now, but feel free to open a new issue with a more descriptive title and body.

[bigfootjon]

Refiled as #5739