Prevent printing binary in RPC errors (#1604)

## Issue Addressed

#1566 

## Proposed Changes

Prevents printing binary characters in the RPC error response from peers.

beacon_node/eth2_libp2p/Cargo.toml

@@ -37,6 +37,7 @@ tiny-keccak = "2.0.2"
 environment = { path = "../../lighthouse/environment" }
 # TODO: Remove rand crate for mainnet
 rand = "0.7.3"
+regex = "1.3.9"
 
 [dependencies.libp2p]
 #version = "0.23.0"