pom.xml - update cloudbees-folder version to 6.6
pom.xml - update cloudbees-folder version to 6.6

the current cloudbees-folder version, 5.18, does not work when you have a newer version of the folder plugin, such as with CloudBees  2.138 which has version 6.6 installed.
gabemontero/jenkins-sync-plugin,gabemontero/jenkins-sync-plugin,gabemontero/jenkins-sync-plugin,gabemontero/jenkins-sync-plugin