message: [type] fix type annotation error
diff: @@ -10,6 +10,7 @@ use rand::{rngs::OsRng, Rng};
  use serde::{de::Error as _, Deserialize, Deserializer, Serialize, Serializer};
  use starcoin_crypto::{hash::CryptoHash, HashValue, VerifyingKey};
  use std::{convert::TryFrom, fmt, str::FromStr};
  +use std::borrow::Cow;
  pub const ADDRESS_LENGTH: usize = 16;
  pub const AUTHENTICATION_KEY_LENGTH: usize = ADDRESS_LENGTH * 2;
  @@ -252,7 +253,7 @@ impl<'de> Deserialize<'de> for AccountAddress {
  D: Deserializer<'de>,
  {
  if deserializer.is_human_readable() {
  - let s = serde::private::de::borrow_cow_str(deserializer)?;
  + let s: Cow<str> = serde::private::de::borrow_cow_str(deserializer)?;
  // let s = <&str>::deserialize(deserializer)?;
  AccountAddress::from_str(s.as_ref()).map_err(D::Error::custom)
  } else {
  