chore: Bump werkzeug from 2.3.8 to 3.1.5 in /load_tests

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 2.3.8 to 3.1.5.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/main/CHANGES.rst)
- [Commits](pallets/werkzeug@2.3.8...3.1.5)

---
updated-dependencies:
- dependency-name: werkzeug
  dependency-version: 3.1.5
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]