Bump yargs from 14.2.0 to 15.0.2 in /app

Bumps [yargs](https://github.com/yargs/yargs) from 14.2.0 to 15.0.2.
- [Release notes](https://github.com/yargs/yargs/releases)
- [Changelog](https://github.com/yargs/yargs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/yargs/yargs/compare/v14.2.0...v15.0.2)

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

app/package.json

@@ -36,7 +36,7 @@
     "path": "0.12.7",
     "rxjs": "^6.5.3",
     "rxjs-compat": "^6.5.3",
-    "yargs": "^14.2.0",
+    "yargs": "^15.0.2",
     "zone.js": "^0.8.29"
   },
   "optionalDependencies": {