removed Twitter as contact point, due to inactivity

theme/templates/page.html

@@ -74,7 +74,6 @@
                 <li>Matrix: <a href="https://matrix.to/#/#hackenopenair:stratum0.org">#hackenopenair:stratum0.org</a></li>
 	              <li>IRC: <a href="irc://irc.libera.chat/#hackenopenair">irc.libera.chat/#hackenopenair</a></li>
 	              <li>Mastodon: <a href="https://chaos.social/@HackenOpenAir">@HackenOpenAir@chaos.social</a></li>
-	              <li>Twitter: <a href="https://twitter.com/HackenOpenAir">@HackenOpenAir</a></li>
                 <li><a href="/impressum.html">Impressum und Datenschutzerklärung</a></li>
             </ul>
         <footer>