Use `cryptonite <0.9` on Linux too.
Use `cryptonite <0.9` on Linux too.

The the `<0.9` constraint was only on HaLVM before, but that made no
sense since the 0.8 and 0.9 APIs are incompatible. The (very small)
API change related code is in
c500e4fc50861df6876bc92b9e4d3ad53ae1f55e.

glguy/ssh-hans