build(deps): bump bn.js from 5.2.2 to 5.2.3 in /clients/js-legacy (#586)

Bumps [bn.js](https://github.com/indutny/bn.js) from 5.2.2 to 5.2.3.
- [Release notes](https://github.com/indutny/bn.js/releases)
- [Changelog](https://github.com/indutny/bn.js/blob/master/CHANGELOG.md)
- [Commits](indutny/bn.js@v5.2.2...v5.2.3)

---
updated-dependencies:
- dependency-name: bn.js
  dependency-version: 5.2.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]