message: [network] fix clippy error
  Closes:
  Approved by: phlib9
diff: @@ -36,7 +36,7 @@ pub struct SupportedProtocols(bitvec::BitVec);
  /// The HandshakeMsg contains a mapping from MessagingProtocolVersion suppported by the node to a
  /// bit-vector specifying application-level protocols supported over that version.
  -#[derive(Clone, Debug, Deserialize, Serialize)]
  +#[derive(Clone, Debug, Deserialize, Serialize, Default)]
  pub struct HandshakeMsg {
  pub supported_protocols: BTreeMap<MessagingProtocolVersion, SupportedProtocols>,
  }
  @@ -83,9 +83,7 @@ impl SupportedProtocols {
  impl HandshakeMsg {
  pub fn new() -> Self {
  - HandshakeMsg {
  - supported_protocols: BTreeMap::default(),
  - }
  + Self::default()
  }
  pub fn add(
  