Fix /gh-comments de-serialization of the review state

[Urgau]

It's CHANGES_REQUESTED¹, not REQUEST_CHANGES.

Can be tested with rust-lang/rust#140560.

Footnotes

1. Look for PullRequestReviewState in https://docs.github.com/en/graphql/overview/public-schema. ↩

[ehuss]

I'm unable to get the workflow to run, even though the recent major incident claims to be resolved. It just says "An unexpected error has occurred and we've been automatically notified. Errors are sometimes temporary, so please try again. If the problem persists, please check whether the Actions service is operating normally at https://githubstatus.com. If not, please try again once the outage has been resolved. Should you need to contact Support, please visit https://support.github.com/contact and include request ID: DC15:45691:1402019:1A6413B:69814E06"

I'm going to try closing and reopening.