Temporarily pin voxpupli-test at 1.5
Temporarily pin voxpupli-test at 1.5

Looks like the whiteslace plugin introduced in 2.0 has a few issues.

Temporarily pinning voxpupuli-test at 1.5 to see if this clears the
issues in CI.

voxpupuli/puppet-collectd,voxpupuli/puppet-collectd,voxpupuli/puppet-collectd