(maint) Add upper bound to puppet version

Update the module metadata so that it has an upper bound of puppet
5.0.0.

Author: HAIL9000

metadata.json

@@ -24,7 +24,7 @@
   "requirements": [
     {
       "name": "puppet",
-      "version_requirement": ">= 3.7.0"
+      "version_requirement": ">= 3.7.0 < 5.0.0"
     }
   ]
 }