Bump browserify-sign from 4.2.1 to 4.2.2 in /browser/flagr-ui (#556)

Bumps [browserify-sign](https://github.com/crypto-browserify/browserify-sign) from 4.2.1 to 4.2.2.
- [Changelog](https://github.com/browserify/browserify-sign/blob/main/CHANGELOG.md)
- [Commits](browserify/browserify-sign@v4.2.1...v4.2.2)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>