send outbound link events to GA4

src/virtualhosts/www/javascript/scripts.js

@@ -257,11 +257,9 @@ function trackOutboundRepoLinks() {
 
 // Send Outbound link clicks to Google Analytics for logging
 function handleOutboundLinkClicks(event) {
-    if (typeof ga === "function") {  // check for Google Analytics
-        ga('send', 'event', {
-            eventCategory: 'Outbound Link',
-            eventAction: 'click',
-            eventLabel: event.target.href
+    if (typeof gtag === "function") {  // check for Google Analytics 4
+        gtag('event', 'outbound_repo_link', {
+            'holding_repo_url': event.target.href
         });
     }