修改观察者模式提示连接设备bug；新版本设备连接bug；单开限定

ProjectSettings/GraphicsSettings.asset

@@ -38,7 +38,6 @@ GraphicsSettings:
   - {fileID: 16000, guid: 0000000000000000f000000000000000, type: 0}
   - {fileID: 16001, guid: 0000000000000000f000000000000000, type: 0}
   - {fileID: 17000, guid: 0000000000000000f000000000000000, type: 0}
-  - {fileID: 16003, guid: 0000000000000000f000000000000000, type: 0}
   m_PreloadedShaders: []
   m_SpritesDefaultMaterial: {fileID: 10754, guid: 0000000000000000f000000000000000,
     type: 0}

ProjectSettings/ProjectSettings.asset

@@ -86,7 +86,7 @@ PlayerSettings:
   submitAnalytics: 1
   usePlayerLog: 1
   bakeCollisionMeshes: 0
-  forceSingleInstance: 0
+  forceSingleInstance: 1
   useFlipModelSwapchain: 1
   resizableWindow: 0
   useMacAppStoreValidation: 0