See motivation at #1503 (comment).

I will be pinging the repos which are already using the org secret to let them know we'll be switching the org secret over to a fine-grained PAT.

Current target is to make this switch on Wed, June 28 (I'm on vacation next week so want to wait until afterwards in case any issues).

After we switch the org secret over to the fine-grained PAT, I'll revoke the old PAT.