Fix Rust beta compiler errors 1.78.0-beta.1 (#5439)

* remove redundant imports

* fix test

* contains key

* fmt

* Merge branch 'unstable' into fix-beta-compiler

crypto/eth2_wallet/src/json_wallet/mod.rs

@@ -1,6 +1,5 @@
 use serde::{Deserialize, Serialize};
 use serde_repr::*;
-use std::convert::TryFrom;
 
 pub use eth2_keystore::json_keystore::{
     Aes128Ctr, ChecksumModule, Cipher, CipherModule, Crypto, EmptyMap, EmptyString, Kdf, KdfModule,

crypto/eth2_wallet/src/validator_path.rs

@@ -1,5 +1,4 @@
 use std::fmt;
-use std::iter::Iterator;
 
 pub const PURPOSE: u32 = 12381;
 pub const COIN_TYPE: u32 = 3600;