chore: add renovate

Author: mrlubos

renovate.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["config:recommended"],
+  "schedule": ["before 3am on Monday"],
+  "prConcurrentLimit": 4,
+  "minimumReleaseAge": "3 days"
+}