deps: bump com.google.cloud:google-cloud-spanner-jdbc (#949)

Bumps [com.google.cloud:google-cloud-spanner-jdbc](https://github.com/googleapis/java-spanner-jdbc) from 2.15.5 to 2.16.0.
- [Release notes](https://github.com/googleapis/java-spanner-jdbc/releases)
- [Changelog](https://github.com/googleapis/java-spanner-jdbc/blob/main/CHANGELOG.md)
- [Commits](googleapis/java-spanner-jdbc@v2.15.5...v2.16.0)

---
updated-dependencies:
- dependency-name: com.google.cloud:google-cloud-spanner-jdbc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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