Bump io.reactivex.rxjava2:rxjava from 2.2.7 to 2.2.21 (#188)

Bumps [io.reactivex.rxjava2:rxjava](https://github.com/ReactiveX/RxJava) from 2.2.7 to 2.2.21.
- [Release notes](https://github.com/ReactiveX/RxJava/releases)
- [Changelog](https://github.com/ReactiveX/RxJava/blob/v2.2.21/CHANGES.md)
- [Commits](ReactiveX/RxJava@v2.2.7...v2.2.21)

---
updated-dependencies:
- dependency-name: io.reactivex.rxjava2:rxjava
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

gradle/libs.versions.toml

@@ -20,7 +20,7 @@ mockito = "org.mockito:mockito-core:4.11.0"
 reactor-core = { module = "io.projectreactor:reactor-core", version.ref = "reactorCore" }
 reactor-test = { module = "io.projectreactor:reactor-test", version.ref = "reactorCore" }
 reactor-extra = { module = "io.projectreactor.addons:reactor-extra", version.ref = "reactorAddons" }
-rxjava2 = "io.reactivex.rxjava2:rxjava:2.2.7"
+rxjava2 = "io.reactivex.rxjava2:rxjava:2.2.21"
 slf4j = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
 slf4j-jcl = { module = "org.slf4j:jcl-over-slf4j", version.ref = "slf4j" }