GH-41002: [CI][Python] Remove pytest-cython pin

[pitrou]

Rationale for this change

pytest-cython has been released with the relevant bugfix.

Are these changes tested?

Yes, by existing CI builds.

Are there any user-facing changes?

No.

• GitHub Issue: [CI][Python] Remove pins connected to pytest-cython #41002

[github-actions]

⚠️ GitHub issue #41002 has been automatically assigned in GitHub to PR creator.

[pitrou]

@github-actions crossbow submit -g python

[github-actions]

Revision: 28ae00c

Submitted crossbow builds: ursacomputing/crossbow @ actions-ba341bb11c

Task	Status
example-python-minimal-build-fedora-conda
example-python-minimal-build-ubuntu-venv
test-conda-python-3.10
test-conda-python-3.10-cython2
test-conda-python-3.10-hdfs-2.9.2
test-conda-python-3.10-hdfs-3.2.1
test-conda-python-3.10-pandas-latest-numpy-latest
test-conda-python-3.10-substrait
test-conda-python-3.11
test-conda-python-3.11-dask-latest
test-conda-python-3.11-dask-upstream_devel
test-conda-python-3.11-hypothesis
test-conda-python-3.11-pandas-latest-numpy-1.26
test-conda-python-3.11-pandas-latest-numpy-latest
test-conda-python-3.11-pandas-nightly-numpy-nightly
test-conda-python-3.11-pandas-upstream_devel-numpy-nightly
test-conda-python-3.11-spark-master
test-conda-python-3.12
test-conda-python-3.12-cpython-debug
test-conda-python-3.13
test-conda-python-3.9
test-conda-python-3.9-pandas-1.1.3-numpy-1.19.5
test-conda-python-emscripten
test-cuda-python-ubuntu-22.04-cuda-11.7.1
test-debian-12-python-3-amd64
test-debian-12-python-3-i386
test-fedora-39-python-3
test-ubuntu-22.04-python-3
test-ubuntu-22.04-python-313-freethreading
test-ubuntu-24.04-python-3

[pitrou]

Well, it looks like the newer pytest-cython triggers an error in the hypothesis CI build:
https://github.com/ursacomputing/crossbow/actions/runs/12296705269/job/34316261656#step:7:5932

+ pytest -r s -m hypothesis -W error --pyargs pyarrow
/opt/conda/envs/arrow/lib/python3.11/site-packages/pytest_cython/__init__.py:2: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
  from pkg_resources import get_distribution
/opt/conda/envs/arrow/lib/python3.11/site-packages/pkg_resources/__init__.py:3154: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/opt/conda/envs/arrow/lib/python3.11/site-packages/pytest_cython/plugin.py:36: PytestRemovedIn9Warning: The (path: py.path.local) argument is deprecated, please use (file_path: pathlib.Path)
see https://docs.pytest.org/en/latest/deprecations.html#py-path-local-arguments-for-hooks-replaced-with-pathlib-path
  def pytest_collect_file(file_path: pathlib.Path, path, parent: pytest.Collector) -> pytest.Module:

[pitrou]

cc @AlenkaF