fix test error

Author: mkamalza

com.unity.perception/Editor/GroundTruth/PerceptionCameraEditor.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 using UnityEditor.Perception.Visualizer;
 using UnityEditorInternal;
 using UnityEngine;

com.unity.perception/Editor/Visualizer/VisualizerInstaller.cs

@@ -736,7 +736,7 @@ static async Task CheckForUpdates()
                     "Install",
                     "Cancel"))
                 {
-                    SetupVisualizer();
+                    await SetupVisualizer();
                 }
             }
             else