Test Python thread safety with pytest-run-parallel

[cclauss]

https://py-free-threading.github.io
https://pypi.org/project/pytest-run-parallel

% uvx --with="valkey[libvalkey]" python3.14t -c "import valkey"

Installed 2 packages in 5ms
<frozen importlib._bootstrap>:491: RuntimeWarning: The global interpreter lock (GIL) has been enabled to
    load module 'libvalkey.libvalkey', which has not declared that it can run safely without the GIL.
    To override this behavior and keep the GIL disabled (at your own risk), run with PYTHON_GIL=0 or -Xgil=0.

[Copilot]

Pull Request Overview

This PR updates the CI infrastructure and testing strategy by bumping GitHub Actions versions, adding parallel test execution capabilities, and dropping support for Python 3.8 and PyPy 3.8.

• Upgraded GitHub Actions (actions/checkout v4→v5, actions/setup-python v5→v6)
• Added pytest-run-parallel for running tests multiple times in parallel
• Removed Python 3.8 and PyPy 3.8 from the test matrix

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
dev_requirements.txt	Added pytest-run-parallel dependency for parallel test execution
.github/workflows/integration.yaml	Updated GitHub Actions versions, removed Python 3.8 support, and enabled parallel test execution with 8 iterations

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Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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Pull Request Overview

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[mkmkme]

Closing due to lack of support for free threaded Python in this module at this moment. See #52 (comment)