Replace bitmask with bitflags (#7159)

Signed-off-by: koushiro <koushiro.cqx@gmail.com>

substrate/frame/elections/src/lib.rs

@@ -41,7 +41,7 @@ use frame_support::{
 	weights::{Weight, DispatchClass},
 	traits::{
 		Currency, ExistenceRequirement, Get, LockableCurrency, LockIdentifier, BalanceStatus,
-		OnUnbalanced, ReservableCurrency, WithdrawReason, WithdrawReasons, ChangeMembers,
+		OnUnbalanced, ReservableCurrency, WithdrawReasons, ChangeMembers,
 	}
 };
 use codec::{Encode, Decode};
@@ -871,7 +871,7 @@ impl<T: Trait> Module<T> {
 						let imbalance = T::Currency::withdraw(
 							&who,
 							T::VotingFee::get(),
-							WithdrawReason::Fee.into(),
+							WithdrawReasons::FEE,
 							ExistenceRequirement::KeepAlive,
 						)?;
 						T::BadVoterIndex::on_unbalanced(imbalance);