pool: Fix AIO test

Regression came with d58930b.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

pool/pool_aio_test.go

@@ -723,7 +723,7 @@ func testCreateContainer(ctx context.Context, t *testing.T, signer neofscrypto.S
 
 	var pp netmap.PlacementPolicy
 	pp.SetContainerBackupFactor(1)
-	pp.SetReplicas(rd)
+	pp.SetReplicas([]netmap.ReplicaDescriptor{rd})
 
 	cont.SetPlacementPolicy(pp)