Bump browserify-sign from 4.2.0 to 4.2.2 in /frontend/zulu

Bumps [browserify-sign](https://github.com/crypto-browserify/browserify-sign) from 4.2.0 to 4.2.2.
- [Changelog](https://github.com/browserify/browserify-sign/blob/main/CHANGELOG.md)
- [Commits](browserify/browserify-sign@v4.2.0...v4.2.2)

---
updated-dependencies:
- dependency-name: browserify-sign
  dependency-type: indirect
...

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