Add dosfstools to bindep

This is required by the new overcloud-hardened-uefi-full-centos-8 jobs
which build images from git cloned projects.

Change-Id: Id5c8ba02762ab87fab5f8121dda37b463466c050

bindep.txt

@@ -3,6 +3,7 @@
 
 xfsprogs [platform:rpm test]
 qemu-img [platform:rpm test]
+dosfstools [platform:rpm test]
 libffi-dev [platform:dpkg]
 libffi-devel [platform:rpm]
 libssl-dev [platform:dpkg test]