Update Xstatic-angular version in ``requirements.txt``
Update Xstatic-angular version in ``requirements.txt``

As horizon already migrated to Xstatic-angular version 1.8.2.2
from 1.5.8.0 by patch f044c4b0a3. This patch updates xstatic-angular
version in ``requirements.txt``.

Change-Id: I3a7178fb6b558469f7cc746a56c6bab1dd4dc1e6

openstack/horizon,openstack/horizon,openstack/horizon,openstack/horizon