change ReplaceEvent() interface to return a list of the events deleted.

khatru/adding.go

@@ -46,7 +46,7 @@ func (rl *Relay) handleNormal(ctx context.Context, evt nostr.Event) (skipBroadca
 	} else {
 		// otherwise it's a replaceable
 		if nil != rl.ReplaceEvent {
-			if err := rl.ReplaceEvent(ctx, evt); err != nil {
+			if _, err := rl.ReplaceEvent(ctx, evt); err != nil {
 				switch err {
 				case eventstore.ErrDupEvent:
 					return true, nil