Bump the security group with 2 updates (willswire#175)

Bumps the security group with 2 updates: [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest) and [@vitest/coverage-istanbul](https://github.com/vitest-dev/vitest/tree/HEAD/packages/coverage-istanbul).


Updates `vitest` from 2.1.8 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-istanbul` from 2.1.8 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-istanbul)

---
updated-dependencies:
- dependency-name: vitest
  dependency-type: direct:development
  dependency-group: security
- dependency-name: "@vitest/coverage-istanbul"
  dependency-type: direct:development
  dependency-group: security
...

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