fix: change 2020 typo to 2021 in header

Author: jarrettch

public/_partials/shared/header.ejs

@@ -11,7 +11,7 @@
             <li>
               <a href="/events/2021">Past Talks</a>
               <ul>
-                  <li><a href="/events/2021">2020</a></li>
+                  <li><a href="/events/2021">2021</a></li>
                   <li><a href="/events/2020">2020</a></li>
                   <li><a href="/events/2019">2019</a></li>
                   <li><a href="/events/2018">2018</a></li>