Bump shelljs from 0.7.8 to 0.8.5 in /frontend

Bumps [shelljs](https://github.com/shelljs/shelljs) from 0.7.8 to 0.8.5.
- [Release notes](https://github.com/shelljs/shelljs/releases)
- [Changelog](https://github.com/shelljs/shelljs/blob/master/CHANGELOG.md)
- [Commits](shelljs/shelljs@v0.7.8...v0.8.5)

---
updated-dependencies:
- dependency-name: shelljs
  dependency-type: indirect
...

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