remove unnecessary option

server.js

@@ -17,7 +17,7 @@ let template // generated by html-webpack-plugin
 let renderer  // created from the webpack-generated server bundle
 if (isProd) {
   // in production: create server renderer and index HTML from real fs
-  renderer = createRenderer(require('./dist/vue-ssr-bundle.json'), 'utf-8')
+  renderer = createRenderer(require('./dist/vue-ssr-bundle.json'))
   template = fs.readFileSync(resolve('./dist/index.html'), 'utf-8')
 } else {
   // in development: setup the dev server with watch and hot-reload,