[web] Fixed copyright year.

web/layouts/partials/global-footer-nav.html

 <footer class="text-gray-700 body-font">
   <div class="px-5 py-8 mx-auto flex items-center sm:flex-row flex-col">
-    <p class="text-sm text-gray-500 sm:ml-4 sm:pl-4 sm:border-gray-200 sm:py-2 sm:mt-0 mt-4 mb-0">© 2020
+    <p class="text-sm text-gray-500 sm:ml-4 sm:pl-4 sm:border-gray-200 sm:py-2 sm:mt-0 mt-4 mb-0">© {{ dateFormat "2006" now }}
       OpenGeoSys Community, <a href="/imprint">Privacy policy / Legal statements / Impressum</a></p>
     <span class="inline-flex sm:ml-auto sm:mt-0 mt-4 justify-center sm:justify-start">