fix: enable forkProcessing to make Renovate work for this repo

Since Renovate is running in autodiscover mode and this repo is a fork,
enable forkProcessing to have Renovate work for this repo.

https://docs.renovatebot.com/configuration-options/#forkprocessing

renovate.json

@@ -2,5 +2,6 @@
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": [
     "config:recommended"
-  ]
-}
+  ],
+  "forkProcessing": "enabled"
+}