Merge pull request #523 from puppetlabs/CONT-802-add_puppet8_support

(CONT-802) - add puppet 8/drop puppet 6

Author: david22swan

.fixtures.yml

@@ -7,7 +7,7 @@ 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: