chore: Add minimumReleaseAge of 7 days to renovate.json (#5171)

Adds `minimumReleaseAge: "7 days"` to the root of `renovate.json` to
enforce a 7-day delay on non-security updates across all dependencies,
helping mitigate the risk of pulling in malicious packages.

---
*PR created automatically by Jules for task
[15104474353265659662](https://jules.google.com/task/15104474353265659662)
started by @another-rex*

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: another-rex

renovate.json

@@ -9,6 +9,7 @@
   ],
   "prHourlyLimit": 0,
   "prConcurrentLimit": 20,
+  "minimumReleaseAge": "7 days",
   "labels": [
     "dependencies"
   ],