Add missing Schedule call to allow individual tests from TestSceneMessageNotifier to pass

osu.Game.Tests/Visual/Online/TestSceneMessageNotifier.cs

@@ -30,7 +30,7 @@ namespace osu.Game.Tests.Visual.Online
         private int messageIdCounter;
 
         [SetUp]
-        public void Setup()
+        public void Setup() => Schedule(() =>
         {
             if (API is DummyAPIAccess daa)
             {
@@ -50,7 +50,7 @@ namespace osu.Game.Tests.Visual.Online
 
                 testContainer.ChatOverlay.Show();
             });
-        }
+        });
 
         private bool dummyAPIHandleRequest(APIRequest request)
         {