build(deps-dev): bump types-python-dateutil from 2.9.0.20250708 to 2.9.0.20250809 in /clients/python (kubeflow#1445)

Bumps [types-python-dateutil](https://github.com/typeshed-internal/stub_uploader) from 2.9.0.20250708 to 2.9.0.20250809.
- [Commits](https://github.com/typeshed-internal/stub_uploader/commits)

---
updated-dependencies:
- dependency-name: types-python-dateutil
  dependency-version: 2.9.0.20250809
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]