fix check nmapexist on debian
fix check nmapexist on debian

command is a shell-buitin, so `command -v nmap` must use shell module

Signed-off-by: Shengjing Zhu <d8b54dd224b165a4ae09ed23421d01d81041bd59@gmail.com>

fgal/ceph-ansible,font/ceph-ansible,WingkaiHo/ceph-ansible,bengland2/ceph-ansible,jtaleric/ceph-ansible,albertomurillo/ceph-ansible,ceph/ceph-ansible,font/ceph-ansible,albertomurillo/ceph-ansible,travmi/ceph-ansible,WingkaiHo/ceph-ansible,WingkaiHo/ceph-ansible,fgal/ceph-ansible,albertomurillo/ceph-ansible,ceph/ceph-ansible,jtaleric/ceph-ansible,bengland2/ceph-ansible,travmi/ceph-ansible