Bump enumn from 0.1.4 to 0.1.5 (#5938)

Bumps [enumn](https://github.com/dtolnay/enumn) from 0.1.4 to 0.1.5.
- [Release notes](https://github.com/dtolnay/enumn/releases)
- [Commits](https://github.com/dtolnay/enumn/compare/0.1.4...0.1.5)

---
updated-dependencies:
- dependency-name: enumn
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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