drop support for puppet7

Author: jhoblitt

metadata.json

@@ -33,7 +33,7 @@
   "requirements": [
     {
       "name": "puppet",
-      "version_requirement": ">= 7.0.0 < 9.0.0"
+      "version_requirement": ">= 8.0.0 < 9.0.0"
     }
   ]
 }