message: remove now unused rand import
diff: @@ -12,7 +12,6 @@ use crate::{
  use chain_core::mempack::{ReadBuf, ReadError, Readable};
  use chain_core::property;
  use chain_crypto::{Curve25519_2HashDH, FakeMMM, PublicKey, SecretKey};
  -use rand::{Rng, SeedableRng};
  /// Hash of GenesisPraosLeader
  #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
  