message: Fix leftover clippy lint
diff: @@ -16,6 +16,7 @@ use bytes::{Bytes, BytesMut};
  use hex_fmt::HexFmt;
  use openssl::ssl::SslRef;
  use pin_project::pin_project;
  +#[cfg(test)]
  use rand::RngCore;
  use static_assertions::const_assert;
  use tokio_serde::{Deserializer, Serializer};
  