fix(www): don't get stuck on outdated nginx releases
fix(www): don't get stuck on outdated nginx releases

nginx drops support for even release numbers every April, declaring
the next even release number stable:
https://www.nginx.com/blog/nginx-1-16-1-17-released/

This commit ensures that we always use the stable version.

desec-io/desec-stack,desec-io/desec-stack,desec-io/desec-stack,desec-io/desec-stack