multi: update to latest RegisterBlockEpochNtfn interface

discovery/gossiper.go

@@ -408,7 +408,7 @@ func (d *AuthenticatedGossiper) Start() error {
 	// First we register for new notifications of newly discovered blocks.
 	// We do this immediately so we'll later be able to consume any/all
 	// blocks which were discovered.
-	blockEpochs, err := d.cfg.Notifier.RegisterBlockEpochNtfn()
+	blockEpochs, err := d.cfg.Notifier.RegisterBlockEpochNtfn(nil)
 	if err != nil {
 		return err
 	}