fix ts lint warning: Strings must use singlequote

frontend/src/boot/error-handler.ts

@@ -4,14 +4,14 @@ import { Router } from 'vue-router';
 import { App } from 'vue';
 
 export default boot(({ app, router }: { app: App<Element>; router: Router }) => {
-  document.documentElement.lang="ja-JP";
+  document.documentElement.lang='ja-JP';
   app.config.errorHandler = (err: any, instance: any, info: string) => {
     if (err.response && err.response.status === 401) {
       // 認証エラーの場合再ログインする
       console.error('(; ﾟДﾟ)/認証エラー(401)：', err, info);
       localStorage.removeItem('token');
       router.replace({
-        path:"/login",
+        path:'/login',
         query:{redirect:router.currentRoute.value.fullPath}
       });
     } else {