chore: bump mockttp from 2.3.1 to 2.4.0 in /web3.js (#21167)

Bumps [mockttp](https://github.com/httptoolkit/mockttp) from 2.3.1 to 2.4.0.
- [Release notes](https://github.com/httptoolkit/mockttp/releases)
- [Commits](httptoolkit/mockttp@v2.3.1...v2.4.0)

---
updated-dependencies:
- dependency-name: mockttp
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]