Ok, so how would such a secret end up in a commit? E.g., I don't see why I would have my home address anywhere close to a code repository. Maybe if I used the wrong "secret" email address when authoring the commit?

If it's not possible to invalidate your compromised software secrets, I would argue that you have bigger and more urgent problems to fix. But fair enough: Deleting them from GitHub might reduce the impact in such cases.