Update Slack invite link

The previous Slack invite link has expired, and was replaced in the community
repo with a new link set not to expire. Update the community links page on the
website to use the new link.

layouts/partials/community-links.html

@@ -34,7 +34,7 @@ <h2>Reach out</h2>
         <p>Join our community spaces:</p>
         <ul>
           <li><i class="fab fa-slack fa-fw"></i>
-            <a href="https://join.slack.com/t/tektoncd/shared_invite/zt-23f3gmgch-3pKwLCrnh2~HLttlX_4djg">
+            <a href="https://join.slack.com/t/tektoncd/shared_invite/zt-25lfy2wk3-DH1FKFPWG2QQU~EzHa0Vsg">
               Join the Tekton Slack!</a>
           </li>
           <li><i class="fab fa-twitter fa-fw"></i>