`org.apache.sshd` requires `net.i2p.crypto/eddsa` dependency
to work with ED25519 keys.

This worked in 0.40 because `eddsa` was included as a transitive
dependency of another unrelated dependency (`buddy`) but stopped
working in 0.41 because the new version of `buddy` no longer depends
on `eddsa`. Thus, we must explicitly include the dependency.

To prevent this from breaking again, switched one of the test
keys to an ED25519 key.