chore(deps): Bump rxdart

Bumps [rxdart](https://github.com/ReactiveX/rxdart) from 0.27.7 to 0.28.0.
- [Release notes](https://github.com/ReactiveX/rxdart/releases)
- [Commits](ReactiveX/rxdart@0.27.7...0.28.0)

---
updated-dependencies:
- dependency-name: rxdart
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

flutter_news_example/packages/deep_link_client/pubspec.yaml

@@ -10,7 +10,7 @@ dependencies:
   firebase_core: ^3.0.0
   firebase_dynamic_links: ^6.0.0
   plugin_platform_interface: ^2.1.3
-  rxdart: ^0.27.3
+  rxdart: ^0.28.0
 
 dev_dependencies:
   firebase_core_platform_interface: ^5.0.0