pinning puppet version to fix failing spec tests (#346)

* CLOUD-2146-cleanup-of-cocker-compose-acceptance-tests (#341)

* pinning puppet version to fix failing spec tests

Author: MarkW

Gemfile

@@ -7,7 +7,7 @@ group :test do
   elsif puppet_git_url = ENV['PUPPET_GIT_URL']
     gem "puppet", :git => puppet_git_url
   else
-    gem "puppet"
+    gem "puppet", "5.5.6"
   end
   gem "puppet-lint", "2.3.3"
   gem "puppet-lint-unquoted_string-check", "0.3.0"