[fix] we don't use bind9, add null entry to remove it from old services.yml

data/templates/yunohost/services.yml

@@ -51,6 +51,7 @@ nslcd:
    status: service
    log: /var/log/syslog
 nsswitch: null
+bind9: null
 udisks2: null
 amavis: null
 postgrey: null