Update footer

Author: peterbourgon

_src/inc/footer.source

@@ -1,6 +1,6 @@
 <div class="footer">
 <p>
-Copyright &copy; 2014&ndash;2017 <a href="https://peter.bourgon.org">Peter Bourgon</a>
+Copyright &copy; 2014&ndash;2021 <a href="https://peter.bourgon.org">Peter Bourgon</a>
  and <a href="https://github.com/go-kit/kit/contributors">the Go kit contributors</a>. <br/>
 The Go Gopher was designed by <a href="http://reneefrench.blogspot.com">Renée French</a>
  and is licensed under the Creative Commons 3.0 Attributions license.