Update copyright date

Extend the copyright date to this year.

Author: xmarcalx

index.html

@@ -434,7 +434,7 @@
           <a href="#home">
             <img src="img/firecracker-logo@3x.png" alt="Firecracker logo" />
           </a>
-          <div>©2018-2021, Amazon Web Services, Inc. or its affiliates. All rights reserved.</div>
+          <div>©2018-2023, Amazon Web Services, Inc. or its affiliates. All rights reserved.</div>
         </div>
       </footer>
     </section>