[nginx] Add ipv6 listener (RSS-Bridge#3292)

Author: Bockiii

config/nginx.conf

@@ -1,5 +1,6 @@
 server {
     listen 80 default_server;
+    listen [::]:80 default_server;
     root /app;
     access_log /var/log/nginx/rssbridge.access.log;
     error_log /var/log/nginx/rssbridge.error.log;