Bump mock-fs from 5.3.0 to 5.4.0 (#779)

Bumps [mock-fs](https://github.com/tschaub/mock-fs) from 5.3.0 to 5.4.0.
- [Release notes](https://github.com/tschaub/mock-fs/releases)
- [Changelog](https://github.com/tschaub/mock-fs/blob/main/changelog.md)
- [Commits](tschaub/mock-fs@v5.3.0...v5.4.0)

---
updated-dependencies:
- dependency-name: mock-fs
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>