Add IPv6 listener to Nginx, fixes IO error in Rspamd logs

data/conf/nginx/dynmaps.conf

@@ -1,5 +1,6 @@
 server {
   listen 8081;
+  listen [::]:8081;
   index index.php index.html;
   server_name _;
   error_log  /var/log/nginx/error.log;