build(deps): bump certifi from 2023.5.7 to 2024.7.4 in /loadtesting

Bumps [certifi](https://github.com/certifi/python-certifi) from 2023.5.7 to 2024.7.4.
- [Commits](certifi/python-certifi@2023.05.07...2024.07.04)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: indirect
...

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Author: dependabot[bot]