Bump @types/bn.js from 5.1.1 to 5.1.2

Bumps [@types/bn.js](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/bn.js) from 5.1.1 to 5.1.2.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/bn.js)

---
updated-dependencies:
- dependency-name: "@types/bn.js"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>