Require npm 8

This should ask renovate bot to use npm with package.json version v2

Author: HLeithner

package.json

@@ -40,6 +40,7 @@
     ]
   },
   "engines": {
-    "node": ">=16.14"
+    "node": ">=16.14",
+    "npm": ">=8.0"
   }
 }