feat: upgrade @types/bn.js from 4.11.6 to 5.1.5

Snyk has created this PR to upgrade @types/bn.js from 4.11.6 to 5.1.5.

See this package in npm:
https://www.npmjs.com/package/@types/bn.js

See this project in Snyk:
https://app.snyk.io/org/affiliatedkat/project/0fd52e13-9cec-48c7-b5e4-84964f88ee1b?utm_source=github&utm_medium=referral&page=upgrade-pr