Bump rxjs from 6.5.5 to 6.6.0 (#306)

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>

Author: dependabot-preview[bot]

package-lock.json

@@ -21,7 +21,7 @@
     "@angular/platform-browser": "^9.1.0",
     "@angular/platform-browser-dynamic": "^9.1.0",
     "core-js": "^3.6.5",
-    "rxjs": "^6.5.5",
+    "rxjs": "^6.6.0",
     "shepherd.js": "^8.0.1",
     "tslib": "^1.13.0",
     "zone.js": "~0.10.3"