hotfix: google tag insertion

public/index.html

@@ -9,6 +9,7 @@
   <meta name="description" content="Web site created using create-react-app" />
   <link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png" />
   <meta name="naver-site-verification" content="51f2a7555618a60ab6a26eceaf32ce0bb9a0153d" />
+  <script async src="https://www.googletagmanager.com/gtag/js?id=G-Y90QTCHQFQ"></script>
 
   <!--
       manifest.json provides metadata used when your web app is installed on a
@@ -41,5 +42,12 @@
       To create a production bundle, use `npm run build` or `yarn build`.
     -->
 </body>
+<script>
+  window.dataLayer = window.dataLayer || [];
+  function gtag() { dataLayer.push(arguments); }
+  gtag('js', new Date());
+
+  gtag('config', 'G-Y90QTCHQFQ');
+</script>
 
 </html>