message: Expose Utf8StringErr
diff: @@ -18,7 +18,7 @@ pub use crate::coins::{coin, coins, has_coins, Coin, Uint128};
  pub use crate::encoding::Binary;
  pub use crate::errors::{
  contract_err, dyn_contract_err, invalid, unauthorized, underflow, NotFound, NullPointer,
  - ParseErr, SerializeErr, StdError, StdResult,
  + ParseErr, SerializeErr, StdError, StdResult, Utf8StringErr,
  };
  pub use crate::init_handle::{
  log, BankMsg, CosmosMsg, HandleResponse, HandleResult, InitResponse, InitResult, LogAttribute,
  