fix link to telegram group

_includes/header.html

@@ -21,7 +21,7 @@ <h2>What's more?</h2>-->
                       <li>Conference Posters are published <a href="/posters/">on the website</a>.</li>
                       <li>The recordings of the talks and proceedings of OSM Science will be made available after the conference.</li>
                       <li>Follow State of the Map on social media (<a href="https://en.osm.town/@sotm">Mastodon</a> or <a href="https://x.com/sotm">X</a>) and use the hashtag <i>#stateofthemap2024</i>.</li>
-                      <li>Connect with others in our <a href="https://t.me/sotm2018">telegram group chat</a> and share your State of the Map experience!</li>
+                      <li>Connect with others in our <a href="https://t.me/sotm_international">telegram group chat</a> and share your State of the Map experience!</li>
                     </ul>
                   </p>
                   <p>Thanks to our <a href="/#sponsors">sponsors</a> for supporting SotM 2024!</p>