Tweak: wrong FA icon category

Author: egonw

src/index.html

@@ -475,7 +475,7 @@ <h2 id="license" class="text-center text-primary"><i class="fa fa-legal"></i>&nb
     <div class="container">
       <div class="copyright text-center">
         <a target="_blank" href="https://github.com/cdk"><i class="fa fa-github"></i> GitHub</a>&emsp;
-        <a target="_blank" href="https://fosstodon.org/@cdk"><i class="fa fa-mastodon"></i> Mastodon</a>&emsp;
+        <a target="_blank" href="https://fosstodon.org/@cdk"><i class="fa-brands fa-mastodon"></i> Mastodon</a>&emsp;
         <a target="_blank" href="https://twitter.com/the_cdk"><i class="fa fa-twitter"></i> Twitter</a>&emsp;
         |&emsp;
         <span>2024&nbsp;©&nbsp;All rights reserved.