Merge pull request #549 from puppetlabs/CAT-2152

(CAT-2152) Add support for CentOS 9

Author: span786

metadata.json

@@ -26,7 +26,8 @@
       "operatingsystem": "CentOS",
       "operatingsystemrelease": [
         "7",
-        "8"
+        "8",
+        "9"
       ]
     },
     {