spec: require specific python libraries
spec: require specific python libraries

require explicitly either python2 or python3 libraries depending
on the distribution.

Change-Id: Ia881f5e799608eb29963d399eea659e704dd8e8a
Signed-off-by: Sandro Bonazzola <fcb014d63786651910af5db2ecc5316c668188ef@redhat.com>

oVirt/ovirt-hosted-engine-setup,oVirt/ovirt-hosted-engine-setup