Replace GnuPG with Sequoia-PGP to improve compatibility against OpenPGP RFC 9580

[kachick]

https://sequoia-pgp.org/
https://wiki.archlinux.jp/index.php/OpenPGP
https://wiki.archlinux.jp/index.php/GnuPG#OpenPGP_.E3.81.AE.E4.BA.92.E6.8F.9B.E6.80.A7
https://www.rfc-editor.org/rfc/rfc9580.html

https://gitlab.com/sequoia-pgp/sequoia
https://gitlab.com/sequoia-pgp/sequoia-gpg-agent
https://github.com/sequoia-pgp/authenticate-commits
https://github.com/NixOS/nixpkgs/blob/6c843e113714e5e47a446ef949a6c12e028cf669/pkgs/by-name/se/sequoia-sq/package.nix

Looks like https://github.com/cortex/ripasso is also using Sequoia-PGP
https://github.com/NixOS/nixpkgs/blob/6c843e113714e5e47a446ef949a6c12e028cf669/pkgs/tools/security/ripasso/cursive.nix#L20

[kachick]

--export-secret-subkeys

https://superuser.com/questions/1577858/what-is-export-secret-subkeys-used-for

The second form of the command has the special property to render the secret part of the primary key useless; this is a GNU extension to OpenPGP and other implementations can not be expected to successfully import such a key. Its intended use is in generating a full key with an additional signing subkey on a dedicated machine. This command then exports the key without the primary key to the main machine.

ref: #869

[kachick]

https://github.com/NixOS/nixpkgs/blob/64b80bfb316b57cdb8919a9110ef63393d74382a/pkgs/tools/security/gnupg/24.nix#L36C17-L36C27