pkgdep/rhel: install missing sshpass package

Install sshpass package from third party repo
as it is missing from official epel main x86_64
repository for Centos8.

Signed-off-by: Kamil Godzwon <kamilx.godzwon@intel.com>
Change-Id: Ide1899393eabb838bcb686c30dc58e4538f10c12
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/12685


Reviewed-by: Michal Berger <michallinuxstuff@gmail.com>
Reviewed-by: Pawel Piatek <pawelx.piatek@intel.com>
Reviewed-by: Karol Latecki <karol.latecki@intel.com>
Reviewed-by:  <qun.wan@intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>