Extend grafana-renovate-config base preset (#327)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: korniltsev-grafanista

renovate.json

@@ -1,6 +1,7 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": [
+    "github>grafana/grafana-renovate-config//presets/base",
     "security:only-security-updates"
   ]
 }