Merge pull request #213 from puppetlabs/CONT-777-add_puppet8_support

(Cont 777) - add puppet 8 support/drop puppet 6 support

Author: GSPatton

.fixtures.yml

@@ -6,7 +6,7 @@ fixtures:
     facts: 'https://github.com/puppetlabs/puppetlabs-facts.git'
     puppet_agent:
       repo: 'https://github.com/puppetlabs/puppetlabs-puppet_agent.git'
-      ref: v4.12.1
+      ref: v4.13.0
     provision: 'https://github.com/puppetlabs/provision.git'
   symlinks:
     exec: "#{source_dir}"