Bump immutable from 5.1.4 to 5.1.8

Bumps [immutable](https://github.com/immutable-js/immutable-js) from 5.1.4 to 5.1.8.
- [Release notes](https://github.com/immutable-js/immutable-js/releases)
- [Changelog](https://github.com/immutable-js/immutable-js/blob/main/CHANGELOG.md)
- [Commits](immutable-js/immutable-js@v5.1.4...v5.1.8)

---
updated-dependencies:
- dependency-name: immutable
  dependency-version: 5.1.8
  dependency-type: indirect
...

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

Author: dependabot[bot]