Zabbix Check Fix (#48)

Co-authored-by: muppeth <muppeth@disroot.org>
Reviewed-on: #48
Reviewed-by: meaz <meaz@no-reply@disroot.org>

templates/etc/nginx/sites-available/zabbix_check.j2

@@ -7,7 +7,7 @@ server {
     allow 127.0.0.1;
     deny all;
   }
-{% if item.php_check defined and item.php_check == 'true' %}
+{% if item.php_check is defined and item.php_check == 'true' %}
    location ~ ^/(status|ping)$ {
      access_log off;
      allow 127.0.0.1;