Fix door opening sound

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_synth/lib/src/wolf_3d_audio.dart

@@ -6,7 +6,8 @@ import 'package:wolf_3d_engine/wolf_3d_engine.dart';
 import 'package:wolf_3d_synth/src/imf_renderer.dart';
 
 class WolfAudio implements EngineAudio {
-  void debugSoundTest() {
+  @override
+  Future<void> debugSoundTest() async {
     // Play the first 50 sounds with a 2-second gap to identify them
     for (int i = 0; i < 50; i++) {
       Future.delayed(Duration(seconds: i * 2), () {