Remove redundant role=contentinfo from footer (W3C warning fix)

The <footer> element already implies role="contentinfo" per HTML spec.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: canslab1

index.html

@@ -580,7 +580,7 @@ <h2 id="license">License</h2>
 <!-- PRERENDER-END -->
         </article>
     </main>
-    <footer class="site-footer" role="contentinfo">
+    <footer class="site-footer">
         <nav class="footer-nav" aria-label="CANS Lab Software">
             <a href="https://canslab1.github.io/EpiRank/">EpiRank</a>
             <span class="footer-sep">&middot;</span>