To use a PGP key instead of an age key you can set `SOPS_PGP_FP`. (You
can use `gpg -k --fingerprint --fingerprint` to get your PGP encryption
key fingerprint, remove spaces from it).
The internal manifest file already supported a type field, and so I built
from there.
With those changes, I was able to add my PGP key, and update all my
secrets with it, instead of the age key originally generated:
```
% clan secrets key show | jq
{
"key": "ADB6276965590A096004F6D1E114CBAE8FA29165",
"type": "pgp"
}
% clan secrets key update
% for s in $(clan secrets list) ; do clan secrets users add-secret kal-pgp-from-2022-12-to-2024-12 "$s"; done
% for s in $(clan secrets list) ; do clan secrets users remove-secret --debug kal "$s" ; done
```
