Update dependency @nomicfoundation/hardhat-toolbox to v6 (#580)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Eric Lau <ericglau@outlook.com>
Co-authored-by: Cove Marquis-Bortoli <44323490+CoveMB@users.noreply.github.com>

Author: 3 people