Makefile: improve version detection
Makefile: improve version detection

Prior to this change, if there was a stray tag in the repository that
did not start with a "v", the Makefile would still try to use that tag
as a version tag when constructing the RPMs.

Only use the tags that start with "v", in this case.

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