build(deps-dev): bump rxjs from 7.5.3 to 7.5.4 (#1062)

Bumps [rxjs](https://github.com/reactivex/rxjs) from 7.5.3 to 7.5.4.
- [Release notes](https://github.com/reactivex/rxjs/releases)
- [Changelog](https://github.com/ReactiveX/rxjs/blob/master/CHANGELOG.md)
- [Commits](ReactiveX/rxjs@7.5.3...7.5.4)

---
updated-dependencies:
- dependency-name: rxjs
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

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

package.json

@@ -137,7 +137,7 @@
         "prettier": "^1.19.1",
         "prettier-eslint": "^13.0.0",
         "prettier-tslint": "^0.4.2",
-        "rxjs": "^7.5.3",
+        "rxjs": "^7.5.4",
         "semantic-release": "^19.0.2",
         "sinon-chrome": "^3.0.1",
         "ts-jest": "^25.5.1",