GH-35853: [Python] Fix deprecation warnings from NumPy NEP50

[danepitkin]

Rationale for this change

Remove warnings from the pyarrow test suite (preventing them from eventually becoming errors).

Are these changes tested?

Yes, verified no warnings are displayed.

$ python -m pytest pyarrow/tests/test_array.py -k test_cast_integers_unsafe
=================================================================== test session starts ===================================================================
platform darwin -- Python 3.11.2, pytest-7.2.2, pluggy-1.0.0
rootdir: /Users/dane/code/arrow/python, configfile: setup.cfg
plugins: hypothesis-6.70.1, cython-0.2.1, lazy-fixture-0.6.3
collected 237 items / 236 deselected / 1 selected

pyarrow/tests/test_array.py .                                                                                                                       [100%]

============================================================ 1 passed, 236 deselected in 0.24s ============================================================

Are there any user-facing changes?

No.

• Closes: [Python] NumPy NEP50 introduces deprecation of "value based" promotion of scalars #35853

[github-actions]

⚠️ GitHub issue #35853 has been automatically assigned in GitHub to PR creator.

[jorisvandenbossche]

Thanks!

[ursabot]

Benchmark runs are scheduled for baseline = cbc17a9 and contender = e07e22c. e07e22c is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Finished ⬇️1.12% ⬆️0.03%] test-mac-arm
[Finished ⬇️0.33% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.24% ⬆️0.03%] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] e07e22c5 ec2-t3-xlarge-us-east-2
[Finished] e07e22c5 test-mac-arm
[Finished] e07e22c5 ursa-i9-9960x
[Finished] e07e22c5 ursa-thinkcentre-m75q
[Finished] cbc17a98 ec2-t3-xlarge-us-east-2
[Finished] cbc17a98 test-mac-arm
[Finished] cbc17a98 ursa-i9-9960x
[Finished] cbc17a98 ursa-thinkcentre-m75q
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java