Bump json_annotation from 4.8.1 to 4.9.0

Bumps [json_annotation](https://github.com/google/json_serializable.dart) from 4.8.1 to 4.9.0.
- [Release notes](https://github.com/google/json_serializable.dart/releases)
- [Commits](google/json_serializable.dart@json_annotation-v4.8.1...json_annotation-v4.9.0)

---
updated-dependencies:
- dependency-name: json_annotation
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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