[Security] Bump bower from 1.8.4 to 1.8.8 in /build

Bumps [bower](https://github.com/bower/bower) from 1.8.4 to 1.8.8. **This update includes security fixes.**
- [Release notes](https://github.com/bower/bower/releases)
- [Changelog](https://github.com/bower/bower/blob/master/CHANGELOG.md)
- [Commits](https://github.com/bower/bower/compare/v1.8.4...v1.8.8

)

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