Bump webdriverio from 8.20.0 to 8.20.4 in /testing

Bumps [webdriverio](https://github.com/webdriverio/webdriverio/tree/HEAD/packages/webdriverio) from 8.20.0 to 8.20.4.
- [Release notes](https://github.com/webdriverio/webdriverio/releases)
- [Changelog](https://github.com/webdriverio/webdriverio/blob/main/CHANGELOG.md)
- [Commits](https://github.com/webdriverio/webdriverio/commits/v8.20.4/packages/webdriverio)

---
updated-dependencies:
- dependency-name: webdriverio
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>