Bump gts from 4.0.0 to 5.3.1 in /samples/node-contract

Bumps [gts](https://github.com/google/gts) from 4.0.0 to 5.3.1.
- [Release notes](https://github.com/google/gts/releases)
- [Changelog](https://github.com/google/gts/blob/main/CHANGELOG.md)
- [Commits](google/gts@v4.0.0...v5.3.1)

---
updated-dependencies:
- dependency-name: gts
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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