Add new key to distsigkey.gpg

The new key is

pub brainpoolP384r1 2026-02-23 [SC] [expires: 2034-02-23]

1493269DE61F124AA69A316E3ADF34EBDBB200A4

uid GnuPG.com (Release Signing Key 2026)

with the private part (as all those keys) on a token under control by
key people at g10 Code.