Bump bn.js from 5.1.1 to 5.1.2 in /token (solana-labs#12)

Bumps [bn.js](https://github.com/indutny/bn.js) from 5.1.1 to 5.1.2.
- [Release notes](https://github.com/indutny/bn.js/releases)
- [Changelog](https://github.com/indutny/bn.js/blob/master/CHANGELOG.md)
- [Commits](indutny/bn.js@v5.1.1...v5.1.2)

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