(CONT-809) Updating puppet_agent pin in fixtures

Author: GSPatton

.fixtures.yml

@@ -1,7 +1,9 @@
 fixtures:
   repositories:
     "facts": "https://github.com/puppetlabs/puppetlabs-facts.git"
-    "puppet_agent": "https://github.com/puppetlabs/puppetlabs-puppet_agent.git"
     "puppet_conf": "https://github.com/puppetlabs/puppetlabs-puppet_conf.git"
+    puppet_agent:
+      repo: 'https://github.com/puppetlabs/puppetlabs-puppet_agent.git'
+      ref: v4.13.0
   symlinks:
     "provision": "#{source_dir}"