message: fix payload serialization for Dummy Agent
diff: @@ -4,6 +4,7 @@ use domain::protocol_type::{ProtocolType, ProtocolTypes};
  use std::collections::HashMap;
  #[derive(Deserialize, Serialize, Debug)]
  +#[serde(untagged)]
  pub enum Payloads {
  PayloadV1(PayloadV1),
  PayloadV2(PayloadV2),
  