Enable Gitea SSH via IPv6

closes #612

site-cookbooks/kosmos_gitea/templates/default/nginx_conf_ssh.erb

@@ -4,5 +4,6 @@ upstream _gitea_ssh {
 
 server {
   listen <%= "#{node['openresty']['listen_ip']}:" if node['openresty']['listen_ip'] %>22;
+  listen [::]:22;
   proxy_pass _gitea_ssh;
 }