remove useless import

src/main/main.ts

@@ -9,7 +9,7 @@
  * `./src/main.js` using webpack. This gives us some performance wins.
  */
 import path from 'path';
-import { app, BrowserWindow, ipcMain, shell } from 'electron';
+import { app, BrowserWindow, dialog, ipcMain, shell } from 'electron';
 import { autoUpdater } from 'electron-updater';
 import log from 'electron-log';
 import { resolveHtmlPath } from './util';
@@ -147,4 +147,4 @@ app
 
   ipcMain.on('new-window', (event, url: string) => {
     shell.openExternal(url);
-  });
+  });