Update our signing key, 2021 edition
This includes:
- Bump expiration dates
- Revoke kibi's subkey
- Add boyska's subkey
There's some inspiration for reviewing this in processes/OpenPGP.mdwn in internal.git.
Like last year, I adjusted the steps (and skipped some) because we're not meeting in person.
Closes #17734 (closed)
Edited by intrigeri