fix nginx acme challenge location

templates/nginx.conf.j2

@@ -8,10 +8,10 @@ server {
     return 301 https://$host$request_uri;
   }
   
-{% if acme_enabled and acme_challenge_dir is defined %}
+{% if acme_enabled %}
   location ^~ /.well-known/acme-challenge/ {
 		allow all;
-		root {{ acme_challenge_dir }};
+		alias {{ acme_config.challenge_dir + (acme_config.challenge_dir.endswith('/') | ternary('', '/')) }};
 		try_files $uri =404;
 	}
 {% endif %}