(PDB-4256) Pin puppetlabs-apt to 6.2.1 in acceptance tests
(PDB-4256) Pin puppetlabs-apt to 6.2.1 in acceptance tests

This commit pins the version of puppetlabs-apt in our acceptances tests
in order to work around a dependency cycle issue which was introduced in
the 6.3.0 release. We plan to drop this pin when the issue is resolved.

puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb