[Anurag-S1ngh]

Summary

Adds PyArrow 26 to the supported range of the Python SDK and to the dependency postcommit matrix.

PyArrow 26 requires NumPy 2 at runtime, so the new test environment installs NumPy 2 while the existing PyArrow 17 to 25 environments keep using NumPy 1.26.4.

Changes

• sdks/python/setup.py: raise the pyarrow upper bound from <26.0.0 to <27.0.0
• sdks/python/tox.ini: add 26 to the py311-pyarrow-... environment, add 26: pyarrow>=26,<27, and make NumPy conditional so 17 to 25 stay on 1.26.4 while 26 uses numpy>=2.0.0,<2.5.0
• sdks/python/test-suites/tox/py311/build.gradle: add testPy311pyarrow-26 and wire it into test and postCommitPyDep

Testing

Installed the SDK from source with Python 3.11, pyarrow==26.0.0 and numpy==2.4.6:

• pytest apache_beam/io/parquetio_test.py -m uses_pyarrow: 35 passed, 1 skipped, 5 deselected
• pytest apache_beam/typehints/arrow_type_compatibility_test.py apache_beam/typehints/schemas_test.py: 821 passed, 5 skipped
• tox c -e py311-pyarrow-26 -k deps resolves pyarrow>=26,<27 and numpy>=2.0.0,<2.5.0
• tox c -e py311-pyarrow-25 -k deps still resolves pyarrow>=25,<26 and numpy==1.26.4

The new full matrix entry runs as testPy311pyarrow-26 for reviewers who want the complete uses_pyarrow suite.

fixes #40919

[github-actions]

📋 Review Summary

This PR adds support for pyarrow 26 by raising the upper bound to <27.0.0 in sdks/python/setup.py and adding the py311-pyarrow-26 test environment in sdks/python/tox.ini and sdks/python/test-suites/tox/py311/build.gradle. Because pyarrow 26 dropped support for numpy 1, the tox configuration appropriately pins numpy>=2.0.0,<2.5.0 for pyarrow 26 while preserving numpy==1.26.4 for earlier pyarrow versions.

🔍 General Feedback

• The changes across setup.py, tox.ini, and build.gradle are clean, well-aligned, and follow the established patterns used for previous dependency updates (such as the recent pandas 2.3 / NumPy 2 split).
• Consider incrementing .github/trigger_files/beam_PostCommit_Python_Dependency.json if you would like to trigger the PostCommit Python Dependency workflow directly on this PR to verify the new testPy311pyarrow-26 Gradle task in CI before merging.

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[github-actions]

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