chore: bump bn.js from 4.12.0 to 4.12.1 (#592)

Bumps [bn.js](https://github.com/indutny/bn.js) from 4.12.0 to 4.12.1.
- [Release notes](https://github.com/indutny/bn.js/releases)
- [Changelog](https://github.com/indutny/bn.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/indutny/bn.js/commits)

---
updated-dependencies:
- dependency-name: bn.js
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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