Bump browserify-sign from 4.2.1 to 4.2.3 in /webapp (#475)

Bumps [browserify-sign](https://github.com/crypto-browserify/browserify-sign) from 4.2.1 to 4.2.3.
- [Changelog](https://github.com/browserify/browserify-sign/blob/main/CHANGELOG.md)
- [Commits](browserify/browserify-sign@v4.2.1...v4.2.3)

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

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