Get rid of rustc_hex in favor of hex (#5370)

* Get rid of rustc_hex in favor of hex

* Use HexDisplay

substrate/bin/node/runtime/Cargo.toml

@@ -13,7 +13,6 @@ repository = "https://github.com/paritytech/substrate/"
 # third-party dependencies
 codec = { package = "parity-scale-codec", version = "1.2.0", default-features = false, features = ["derive"] }
 integer-sqrt = { version = "0.1.2" }
-rustc-hex = { version = "2.0", optional = true }
 serde = { version = "1.0.102", optional = true }
 
 # primitives
@@ -108,7 +107,6 @@ std = [
 	"sp-core/std",
 	"pallet-randomness-collective-flip/std",
 	"sp-std/std",
-	"rustc-hex",
 	"serde",
 	"pallet-session/std",
 	"sp-api/std",

substrate/bin/node/runtime/src/lib.rs

@@ -68,7 +68,6 @@ use impls::{CurrencyToVoteHandler, Author, LinearWeightToFee, TargetedFeeAdjustm
 /// Constant values used within the runtime.
 pub mod constants;
 use constants::{time::*, currency::*};
-use frame_system::Trait;
 
 // Make the WASM binary available.
 #[cfg(feature = "std")]