build(deps): bump rxjs from 6.5.5 to 6.6.0 (#2282) (#2287)

Bumps [rxjs](https://github.com/reactivex/rxjs) from 6.5.5 to 6.6.0.
- [Release notes](https://github.com/reactivex/rxjs/releases)
- [Changelog](https://github.com/ReactiveX/rxjs/blob/6.6.0/CHANGELOG.md)
- [Commits](ReactiveX/rxjs@6.5.5...6.6.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

packages/core/package.json

@@ -71,7 +71,7 @@
     "mutation-testing-metrics": "~1.3.0",
     "progress": "~2.0.0",
     "rimraf": "~3.0.0",
-    "rxjs": "~6.5.1",
+    "rxjs": "~6.6.0",
     "source-map": "~0.7.3",
     "surrial": "~2.0.2",
     "tree-kill": "~1.2.0",