[Trivial] Use 'into_inner' for WeakBoundedVec (#1664)

Prevents authority set clone

substrate/frame/babe/src/tests.rs

@@ -95,7 +95,7 @@ fn first_block_epoch_zero_start() {
 
 		let consensus_log = sp_consensus_babe::ConsensusLog::NextEpochData(
 			sp_consensus_babe::digests::NextEpochDescriptor {
-				authorities: Babe::authorities().to_vec(),
+				authorities: Babe::authorities().into_inner(),
 				randomness: Babe::randomness(),
 			},
 		);