Merge pull request #398 from puppetlabs/pdksync_IAC-1787/main/remove_centos_6_support

pdksync - (IAC-1787) Remove Support for CentOS 6

Author: chelnak

metadata.json

@@ -25,7 +25,6 @@
     {
       "operatingsystem": "CentOS",
       "operatingsystemrelease": [
-        "6",
         "7",
         "8"
       ]