feat: Migrate to gtag and support GA4

public/views/shared/ga.ejs

@@ -1,18 +1,11 @@
 <% if(typeof GA !== 'undefined' && GA) { %>
-<script nonce="<%= cspNonce %>">
-(function (i, s, o, g, r, a, m) {
-    i['GoogleAnalyticsObject'] = r;
-    i[r] = i[r] || function () {
-        (i[r].q = i[r].q || []).push(arguments)
-    }, i[r].l = 1 * new Date();
-    a = s.createElement(o),
-    m = s.getElementsByTagName(o)[0];
-    a.async = 1;
-    a.src = g;
-    m.parentNode.insertBefore(a, m)
-})(window, document, 'script', 'https://www.google-analytics.com/analytics.js', 'ga');
-
-ga('create', '<%= GA %>', 'auto');
-ga('send', 'pageview');
+<script nonce="<%= cspNonce %>" async src="https://www.googletagmanager.com/gtag/js?id=<%= GA %>">
+</script>
+<script>
+window.dataLayer = window.dataLayer || [];
+function gtag(){dataLayer.push(arguments);}
+gtag('js', new Date());
+gtag('config', '<%= GA %>');
+gtag('event', 'page_view');
 </script>
 <% } %>