remove jeremy's twitter (plfa#1093)

Author: wenkokke

data/authors/3-siek.yml

@@ -2,4 +2,3 @@ name: Jeremy G. Siek
 email: jsiek@indiana.edu
 corresponding: true
 github: jsiek
-twitter: jeremysiek

web/templates/footer.html

@@ -29,14 +29,6 @@ <h2 class="footer-heading">$pagetitle$</h2>
                             &nbsp;$author.github$
                         </a>
                     </li>
-                    $if(author.twitter)$
-                    <li>
-                        <a rel="me" href="https://twitter.com/$author.twitter$" title="$author.twitter$">
-                            <i class="fab fa-twitter"></i>
-                            &nbsp;$author.twitter$
-                        </a>
-                    </li>
-                    $endif$
                 </ul>
             </div>
             <div class="footer-col footer-col-3">