build(deps-dev): bump the vitest group across 2 directories with 3 updates

Bumps the vitest group with 1 update in the / directory: [@vitest/coverage-istanbul](https://github.com/vitest-dev/vitest/tree/HEAD/packages/coverage-istanbul).
Bumps the vitest group with 2 updates in the /build/frontend-legacy directory: [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).


Updates `@vitest/coverage-istanbul` from 4.0.17 to 4.0.18
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.18/packages/coverage-istanbul)

Updates `vitest` from 4.0.17 to 4.0.18
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.18/packages/vitest)

Updates `vitest` from 4.0.17 to 4.0.18
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.18/packages/vitest)

Updates `@vitest/coverage-v8` from 4.0.17 to 4.0.18
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.18/packages/coverage-v8)

---
updated-dependencies:
- dependency-name: "@vitest/coverage-istanbul"
  dependency-version: 4.0.18
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: vitest
- dependency-name: vitest
  dependency-version: 4.0.18
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: vitest
- dependency-name: vitest
  dependency-version: 4.0.18
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: vitest
- dependency-name: "@vitest/coverage-v8"
  dependency-version: 4.0.18
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: vitest
...

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Author: dependabot[bot]