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/bls/src/generic_public_key_bytes.rs

@@ -6,7 +6,6 @@ use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_utils::hex::encode as hex_encode;
 use ssz::{Decode, Encode};
-use std::convert::TryInto;
 use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;