Bump `ruff` version in Github CI

[RobertoRoos]

Currently ruff is pinned (https://github.com/sphinx-doc/sphinx-argparse/blob/main/.github/workflows/lint.yml):

    - name: Install Ruff
      run: python -m pip install "ruff==0.5.2"

    - name: Lint with Ruff
      run: ruff check . --output-format github

    - name: Format with Ruff
      run: ruff format . --diff

Considering the lint group in pyproject.toml is not constraint, it seems best to unpin ruff in the CI.