update puppet-systemd upper bound to 8.0.0

Author: TheMeier

metadata.json

@@ -26,7 +26,7 @@
     },
     {
       "name": "puppet/systemd",
-      "version_requirement": ">= 0.4.0 < 7.0.0"
+      "version_requirement": ">= 0.4.0 < 8.0.0"
     }
   ],
   "operatingsystem_support": [