chore(deps-dev): bump rxjs from 6.6.2 to 6.6.3

Bumps [rxjs](https://github.com/reactivex/rxjs) from 6.6.2 to 6.6.3.
- [Release notes](https://github.com/reactivex/rxjs/releases)
- [Changelog](https://github.com/ReactiveX/rxjs/blob/6.6.3/CHANGELOG.md)
- [Commits](ReactiveX/rxjs@6.6.2...6.6.3)

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

package.json

@@ -121,7 +121,7 @@
         "react": "^16.13.1",
         "react-dom": "^16.13.1",
         "react-test-renderer": "^16.13.1",
-        "rxjs": "^6.6.2",
+        "rxjs": "^6.6.3",
         "semantic-release": "^17.1.1",
         "stylelint": "^13.7.0",
         "stylelint-config-standard": "^20.0.0",