Handle JWT errors due to out-of-sync system time

[gr2m]

There are two errors we have to handle

1. The calculated expiration time is in the past

   'Expiration time' claim ('exp') must be a numeric value representing the future time at which the assertion expires

2. The issued at time is in the future

   'Issued at' claim ('iat') must be an Integer representing the time that the assertion was issued

I would catch errors in auth.hook and look for the exp or iat in the error message. If either exists, log a warning, then read out error.headers.date to get GitHub's API time, store the difference to the current system time, and use that difference moving forward when calculating more JWTs.

It can be implemented in a similar way as @octokit/auth-basics built-in request error handling:
https://github.com/octokit/auth-basic.js/blob/68dd4638631c57994be455ee7cfca7c8f0c2de8c/src/request-with-2fa.ts

If anyone would like to give this a shot, PRs welcome. I think it's a fun thing to work on. I'll need to implement this myself eventually, but it's not time critical yet

[copperwall]

I'd love to work on this!

[gr2m]

Great :) Let me know if you have any questions!