Update footer.html to point to hosted Gitlab instead of GitHub

layouts/partials/footer.html

@@ -7,7 +7,7 @@
           {{ end}}
         {{ end }}
     </p>
-    Copyright &copy; 2019 by <a style="color: inherit;" href="https://github.com/redox-os"><b>Redox Developers</b></a>
+    Copyright &copy; 2020 by <a style="color: inherit;" href="https://gitlab.redox-os.org/redox-os"><b>Redox Developers</b></a>
 </footer>
 
 <!-- Google Analytics -->