Use version test instead of version_compare

This test was changed to 'version' in ansible 2.5 [1].

[1] https://docs.ansible.com/ansible/2.8/user_guide/playbooks_tests.html#version-compariso

Change-Id: If27fde3a15e2b611cebdfd26af5b421475cb7488

tasks/nspawn_volume.yml

@@ -85,7 +85,7 @@
         systemd_mounts:
           - what: "/var/lib/machines.raw"
             where: "/var/lib/machines"
-            options: "loop,defaults,noatime,nodiratime,compress=lzo,commit=120,{{ (ansible_kernel is version_compare('4.5', '>=')) | ternary('space_cache=v2', 'space_cache') }}"
+            options: "loop,defaults,noatime,nodiratime,compress=lzo,commit=120,{{ (ansible_kernel is version('4.5', '>=')) | ternary('space_cache=v2', 'space_cache') }}"
             type: "btrfs"
             state: 'started'
             enabled: true