Bumps [cloud.google.com/go/storage](https://github.com/googleapis/google-cloud-go) from 1.12.0 to 1.13.0.
- [Release notes](https://github.com/googleapis/google-cloud-go/releases)
- [Changelog](https://github.com/googleapis/google-cloud-go/blob/master/CHANGES.md)
- [Commits](https://github.com/googleapis/google-cloud-go/compare/spanner/v1.12.0...spanner/v1.13.0)

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