Fixed Brython CDN link

Author: andreburgaud

brython/async/ajax/simple.html

@@ -8,7 +8,7 @@
       integrity="sha256-jYujp4Kf07YDuUF9i1MHo4AnpXUKuHxIUXH7CrHxdKw="
       crossorigin="anonymous" />
     <script
-      src="https://cdnjs.cloudflare.com/ajax/libs/brython/3.0.9/brython.min.js" defer>
+      src="https://cdnjs.cloudflare.com/ajax/libs/brython/3.9.0/brython.min.js" defer>
     </script>
     <script
       src="https://cdnjs.cloudflare.com/ajax/libs/brython/3.9.0/brython_stdlib.min.js" defer>