remove a depreciated option of mainWIndow

lib/main-window.js

@@ -9,8 +9,7 @@ var mainWindow = new BrowserWindow({
   zoomFactor: 1.0,
   webPreferences: {
     blinkFeatures: 'OverlayScrollbars'
-  },
-  standardWindow: false
+  }
 })
 
 const url = path.resolve(__dirname, './main.html')