build(deps): bump tar-fs and @web/test-runner in /frontend

Bumps [tar-fs](https://github.com/mafintosh/tar-fs) to 3.1.1 and updates ancestor dependency [@web/test-runner](https://github.com/modernweb-dev/web/tree/HEAD/packages/test-runner). These dependencies need to be updated together.


Updates `tar-fs` from 2.1.1 to 3.1.1
- [Commits](mafintosh/tar-fs@v2.1.1...v3.1.1)

Updates `@web/test-runner` from 0.15.3 to 0.20.2
- [Release notes](https://github.com/modernweb-dev/web/releases)
- [Changelog](https://github.com/modernweb-dev/web/blob/master/packages/test-runner/CHANGELOG.md)
- [Commits](https://github.com/modernweb-dev/web/commits/@web/test-runner@0.20.2/packages/test-runner)

---
updated-dependencies:
- dependency-name: tar-fs
  dependency-version: 3.1.1
  dependency-type: indirect
- dependency-name: "@web/test-runner"
  dependency-version: 0.20.2
  dependency-type: direct:development
...

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Author: dependabot[bot]