Bump tiny-secp256k1 from 1.1.3 to 1.1.7 in /buidler-contracts

Bumps [tiny-secp256k1](https://github.com/bitcoinjs/tiny-secp256k1) from 1.1.3 to 1.1.7.
- [Commits](bitcoinjs/tiny-secp256k1@v1.1.3...v1.1.7)

---
updated-dependencies:
- dependency-name: tiny-secp256k1
  dependency-version: 1.1.7
  dependency-type: indirect
...

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Author: dependabot[bot]