build(deps-dev): Bump @wdio/cli from 5.14.1 to 5.15.6
build(deps-dev): Bump @wdio/cli from 5.14.1 to 5.15.6

Bumps [@wdio/cli](https://github.com/webdriverio/webdriverio) from 5.14.1 to 5.15.6.
- [Release notes](https://github.com/webdriverio/webdriverio/releases)
- [Changelog](https://github.com/webdriverio/webdriverio/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webdriverio/webdriverio/compare/v5.14.1...v5.15.6)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
percy/percy-webdriverio,percy/percy-webdriverio