fix: replace incorrect attributions on roundup issue tracker.

Remove digital ocean reference replace url to roundup with canonical
not sourceforge url.

Author: rouilj

website/issues/html/page.html

@@ -214,11 +214,9 @@ <h1 id="breadcrumb"><span metal:define-slot="body_title">body title</span></h1>
 <div class="footer">
 <div id="credits">
   <p>
-    Hosted on <a href="https://m.do.co/c/783434964889" title="Hosted on DigitalOcean">DigitalOcean</a>,
-    <br>
     Supported by <a href="https://www.python.org/psf-landing/" title="The Python Software Foundation">The Python Software Foundation</a>,
     <br>
-    Powered by <a href="https://roundup.sourceforge.io" title="Powered by the Roundup Issue Tracker">Roundup</a>
+    Powered by <a href="https://www.roundup-tracker.org" title="Powered by the Roundup Issue Tracker">Roundup</a>
   </p>
 </div> <!-- credits -->
 <!-- Created: Wed Jan 14 11:55:38 EST 2009 -->