Pin ARA to 0.9.1 temporarily
Pin ARA to 0.9.1 temporarily

The next release of ARA (0.10.0) contains a change to the callback
plugin location that /should/ be backwards compatible but let's
control the update to the newer version to be safe and avoid
breaking the gate needlessly.

Change-Id: I32176166e8ebcbfdf0baa8bd7ec30e5ec6d795a5

stackforge/kolla,openstack/kolla,coolsvap/kolla,nihilifer/kolla,coolsvap/kolla,mrangana/kolla,openstack/kolla,stackforge/kolla,stackforge/kolla,dardelean/kolla-ansible,dardelean/kolla-ansible,nihilifer/kolla,rahulunair/kolla,dardelean/kolla-ansible,GalenMa/kolla,rahulunair/kolla,coolsvap/kolla,intel-onp/kolla,mrangana/kolla,intel-onp/kolla,GalenMa/kolla