Set gaGtag to true in website siteConfig.js (pytorch#1873)

Summary:
With Google Analytics 4 we need to use Google Tag Manager, so this should be required now.

Pull Request resolved: pytorch#1873

Reviewed By: saitcakmak

Differential Revision: D46536115

Pulled By: Balandat

fbshipit-source-id: 48620ec42675fa8f6d6c2c27059e751b148ccb71

website/siteConfig.js

@@ -35,6 +35,9 @@ const siteConfig = {
   // Google analytics
   gaTrackingId: 'G-CXN3PGE3CC',
 
+  // Use global site tags (gtag.js) to be compatible with Google Analytics 4
+  gaGtag: true,
+
   // links that will be used in the header navigation bar
   headerLinks: [
     {doc: 'introduction', label: 'Docs'},