debexpo previously checked that ed25519 keys had a length of 256. Since
libgcrypt-1.9.0, this value has been updated to 255. Instead of
adjusting the size, the minimal requirement for ed25519 keys have been
dropped since all keys have a unique length anyway.

See: https://dev.gnupg.org/rCdb7b2c591004868abedbc2c19d3bb2efebf8529d
See: https://lists.gnupg.org/pipermail/gnupg-users/2021-September/065454.html