chore: adds basic renovate.json file

Author: hartmut-co-uk

renovate.json

@@ -0,0 +1,9 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:base",
+    ":dependencyDashboard",
+    "group:all",
+    "schedule:weekly"
+  ]
+}