Build(deps): Bump io.reactivex.rxjava3:rxjava from 3.1.7 to 3.1.8

Bumps [io.reactivex.rxjava3:rxjava](https://github.com/ReactiveX/RxJava) from 3.1.7 to 3.1.8.
- [Release notes](https://github.com/ReactiveX/RxJava/releases)
- [Commits](https://github.com/ReactiveX/RxJava/compare/v3.1.7...v3.1.8

)

---
updated-dependencies:
- dependency-name: io.reactivex.rxjava3:rxjava
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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