build(deps-dev): bump vitest

Bumps the npm_and_yarn group with 1 update in the /ui/litellm-dashboard directory: [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest).


Updates `vitest` from 3.2.4 to 4.1.8
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Changelog](https://github.com/vitest-dev/vitest/blob/main/docs/releases.md)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.1.8/packages/vitest)

---
updated-dependencies:
- dependency-name: vitest
  dependency-version: 4.1.8
  dependency-type: direct:development
  dependency-group: npm_and_yarn
...

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Author: dependabot[bot]