fix root offences

Author: Ank4n

substrate/frame/root-offences/src/mock.rs

@@ -27,7 +27,7 @@ use frame_support::{
 	derive_impl, parameter_types,
 	traits::{ConstU32, ConstU64, OneSessionHandler},
 };
-use pallet_staking::StakerStatus;
+use pallet_staking::{BalanceOf, StakerStatus};
 use sp_runtime::{curve::PiecewiseLinear, testing::UintAuthorityId, traits::Zero, BuildStorage};
 use sp_staking::{EraIndex, SessionIndex};