Python: Bump pytest from 9.0.3 to 9.1.0 across /python workspace

[dependabot]

Motivation & Context

The initial pytest bump updated the root Python workspace dependency, but CI installs the full /python workspace with all packages and extras. Several workspace packages still pinned pytest==9.0.3, which made dependency resolution fail in CI.

Description & Review Guide

Aligned the remaining Python workspace pytest pins and refreshed the lockfile so the workspace resolves consistently with pytest==9.1.0.

• What are the major changes?
  • Updated the root /python workspace to pytest==9.1.0
  • Aligned duplicate pytest pins in ag-ui, devui, and lab
  • Regenerated python/uv.lock
• What is the impact of these changes?
  • Fixes CI dependency resolution failures for the Python workspace
  • Keeps the pytest bump consistent across workspace packages without changing runtime functionality
• What do you want reviewers to focus on?
  • Whether the workspace-level pytest pin alignment and lockfile update fully cover the Python packages participating in CI installation

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

[moonbox3]

@copilot: fix the CI/CD failures

[Copilot]

@copilot: fix the CI/CD failures

Addressed in 47d8b40. I aligned the remaining Python workspace pytest pins in ag-ui, devui, and lab, regenerated python/uv.lock, and verified the CI setup command plus targeted pytest checks succeed.