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

beacon_node/lighthouse_network/src/rpc/rate_limiter.rs

@@ -3,7 +3,6 @@ use crate::rpc::Protocol;
 use fnv::FnvHashMap;
 use libp2p::PeerId;
 use serde::{Deserialize, Serialize};
-use std::convert::TryInto;
 use std::future::Future;
 use std::hash::Hash;
 use std::pin::Pin;