chore: Remove web notification custom sound

Sound is now played on macOS
and Windows by default.
On some Linux distro it may
differ but there it should be
possible to configure it.

lib/widgets/local_notifications_extension.dart

@@ -18,10 +18,6 @@ import 'package:fluffychat/widgets/fluffy_chat_app.dart';
 import 'package:fluffychat/widgets/matrix.dart';
 
 extension LocalNotificationsExtension on MatrixState {
-  static final html.AudioElement _audioPlayer = html.AudioElement()
-    ..src = 'assets/assets/sounds/notification.ogg'
-    ..load();
-
   Future<void> showLocalNotification(Event event) async {
     final roomId = event.room.id;
     if (activeRoomId == roomId) {
@@ -74,8 +70,6 @@ extension LocalNotificationsExtension on MatrixState {
             );
       }
 
-      _audioPlayer.play();
-
       html.Notification(
         title,
         body: body,