Ubuntu: install qemu-img on seed-hypervisor

On systems without qemu-img installed, seed VM provisioning will fail
when creating qcow2 disk images. This is the case with some Ubuntu
images. This change updates the stackhpc.libvirt-vm role to v1.14.1,
which installs qemu-img.

Change-Id: I205b40c142adcbe0deb2ea6296c246533fd49def
Story: 2004960
Task: 42330

requirements.yml

@@ -25,7 +25,7 @@
 - src: stackhpc.libvirt-host
   version: v1.8.2
 - src: stackhpc.libvirt-vm
-  version: v1.13.0
+  version: v1.14.1
 - src: stackhpc.luks
   version: 0.4.0
 - src: stackhpc.mellanox-switch