message: Fix warnings in demo tests about naming.
diff: @@ -768,7 +768,7 @@ fn ledger_demo_works() {
  dest: my_did.clone(),
  type_: "1".to_string(),
  },
  - protocolVersion: 1,
  + protocol_version: 1,
  req_id: nym_req_id,
  signature: None,
  };
  @@ -800,7 +800,7 @@ fn ledger_demo_works() {
  type_: "105".to_string(),
  dest: my_did.clone(),
  },
  - protocolVersion: 1,
  + protocol_version: 1,
  };
  let request = serde_json::to_string(&get_nym_txn).unwrap();
  @@ -826,7 +826,7 @@ fn ledger_demo_works() {
  req_id: u64,
  identifier: String,
  operation: Operation,
  - protocolVersion: u64,
  + protocol_version: u64,
  #[serde(skip_serializing_if = "Option::is_none")]
  signature: Option<String>,
  }
  