Bump rxjs from 6.6.6 to 6.6.7 in /app

Bumps [rxjs](https://github.com/reactivex/rxjs) from 6.6.6 to 6.6.7.
- [Release notes](https://github.com/reactivex/rxjs/releases)
- [Changelog](https://github.com/ReactiveX/rxjs/blob/6.6.7/CHANGELOG.md)
- [Commits](https://github.com/reactivex/rxjs/compare/6.6.6...6.6.7)

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

app/package.json

@@ -37,7 +37,7 @@
     "@terminus-term/node-pty": "0.10.0-terminus.3",
     "npm": "6",
     "path": "0.12.7",
-    "rxjs": "^6.6.6",
+    "rxjs": "^6.6.7",
     "yargs": "^16.2.0",
     "zone.js": "^0.11.4"
   },