Bump browserify from 16.1.1 to 16.2.2 in /frontend

Bumps [browserify](https://github.com/browserify/browserify) from 16.1.1 to 16.2.2.
- [Release notes](https://github.com/browserify/browserify/releases)
- [Changelog](https://github.com/browserify/browserify/blob/master/changelog.markdown)
- [Commits](browserify/browserify@v16.1.1...v16.2.2)

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