chore(deps-dev): bump vitest from 1.2.2 to 1.6.1 in /backend

Bumps [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest) from 1.2.2 to 1.6.1.
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v1.6.1/packages/vitest)

---
updated-dependencies:
- dependency-name: vitest
  dependency-type: direct:development
...

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

Author: dependabot[bot]