Bump either from 1.7.0 to 1.8.0

Bumps [either](https://github.com/bluss/either) from 1.7.0 to 1.8.0.
- [Release notes](https://github.com/bluss/either/releases)
- [Commits](rayon-rs/either@1.7.0...1.8.0)

---
updated-dependencies:
- dependency-name: either
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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