Bump cross-env from 5.1.3 to 5.1.6 in /apps/updatenotification

Bumps [cross-env](https://github.com/kentcdodds/cross-env) from 5.1.3 to 5.1.6.
- [Release notes](https://github.com/kentcdodds/cross-env/releases)
- [Changelog](https://github.com/kentcdodds/cross-env/blob/master/CHANGELOG.md)
- [Commits](https://github.com/kentcdodds/cross-env/compare/v5.1.3...v5.1.6

)

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