Add twitter social icon

Author: closji

templates/_sidebar.html

@@ -45,6 +45,10 @@
             <i class="fab fa-youtube"></i>
         </a>
         &nbsp;
+        <a href="https://twitter.com/SWEbench" target="_blank" rel="noopener noreferrer">
+            <i class="fab fa-twitter"></i>
+        </a>
+        &nbsp;
         <a href="https://join.slack.com/t/swe-bench/shared_invite/zt-36pj9bu5s-o3_yXPZbaH2wVnxnss1EkQ" target="_blank" rel="noopener noreferrer">
             <i class="fab fa-slack"></i>
         </a>