Bump @sap-cloud-sdk/generator in /samples/cds-sample-application

Bumps [@sap-cloud-sdk/generator](https://github.com/SAP/cloud-sdk-js) from 3.8.1 to 3.9.0.
- [Release notes](https://github.com/SAP/cloud-sdk-js/releases)
- [Changelog](https://github.com/SAP/cloud-sdk-js/blob/main/CHANGELOG.md)
- [Commits](SAP/cloud-sdk-js@v3.8.1...v3.9.0)

---
updated-dependencies:
- dependency-name: "@sap-cloud-sdk/generator"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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