Bump json_serializable from 6.6.1 to 6.6.2

Bumps [json_serializable](https://github.com/google/json_serializable.dart) from 6.6.1 to 6.6.2.
- [Commits](google/json_serializable.dart@json_serializable-v6.6.1...json_serializable-v6.6.2)

---
updated-dependencies:
- dependency-name: json_serializable
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]