Merge pull request #1001 from saz/require-systemd6

require puppet/systemd >= 6.0.0

Author: wyardley

metadata.json

@@ -66,7 +66,7 @@
     },
     {
       "name": "puppet/systemd",
-      "version_requirement": ">= 4.0.0 < 8.0.0"
+      "version_requirement": ">= 6.0.0 < 8.0.0"
     }
   ],
   "tags": [