Update Renovate Configuration (#161)

Add labels to renovate

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/161

renovate.json

@@ -1,5 +1,6 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "labels": ["dependencies"],
   "extends": [
     "config:base"
   ]