chore(deps): bump google-genai from 1.15.0 to 1.28.0 in /backend
Bumps [google-genai](https://github.com/googleapis/python-genai) from 1.15.0 to 1.28.0.
- [Release notes](https://github.com/googleapis/python-genai/releases)
- [Changelog](https://github.com/googleapis/python-genai/blob/main/CHANGELOG.md)
- [Commits](https://github.com/googleapis/python-genai/compare/v1.15.0...v1.28.0)
---
updated-dependencies:
- dependency-name: google-genai
dependency-version: 1.28.0
dependency-type: direct:production
update-type: version-update:semver-minor
...
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dependabot[bot]