build(deps-dev): bump vitest and @vitest/coverage-v8

Bumps [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest) and [@vitest/coverage-v8](https://github.com/vitest-dev/vitest/tree/HEAD/packages/coverage-v8). These dependencies needed to be updated together.

Updates `vitest` from 2.1.6 to 2.1.9
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v2.1.9/packages/vitest)

Updates `@vitest/coverage-v8` from 2.1.6 to 2.1.9
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v2.1.9/packages/coverage-v8)

---
updated-dependencies:
- dependency-name: vitest
  dependency-version: 2.1.9
  dependency-type: direct:development
- dependency-name: "@vitest/coverage-v8"
  dependency-version: 2.1.9
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]