Update IRC link to use libera.chat

Author: darksidelemm

index.html

@@ -134,7 +134,7 @@ <h2>Contribute</h2>
                 <br/>
                 A huge thanks to RGP for developing the mobile tracker that this site is based on.
                 <br/>
-                You can also find us on IRC in <a href="http://webchat.freenode.net/?channels=highaltitude" target="_blank">#highaltitude</a> at <b>irc.freenode.org</b>.
+                You can also find us on IRC in <a href="https://kiwiirc.com/nextclient/irc.libera.chat/highaltitude" target="_blank">#highaltitude</a> at <b>libera.chat</b>.
             </p>
         </div>
     </div>