Mark non-security md5 usage to allow for compatibility with fips environments

[mykaul]

Summary

• Cherry-pick of apache/cassandra-python-driver@f685c2c
• Marks the non-security md5 usage in MD5Token.hash_fn with usedforsecurity=False so the driver works in FIPS-enforced Python environments, which reject non-approved hash algorithms unless explicitly marked as not used for security purposes.

Test plan

• Ran the unit test suite (tests/unit) locally; test_metadata.py passes in full, including all MD5Token/Token tests
• Remaining failures in the full suite are pre-existing environment gaps (missing optional Cython/Twisted/lz4 dependencies), unrelated to this change

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ℹ️ Recent review info

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Configuration used: Organization UI

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Run ID: b14a293f-da07-46d0-8131-3f4ed62de1a2

📥 Commits

Reviewing files that changed from the base of the PR and between 1d7e601 and d940fd5.

📒 Files selected for processing (1)

• cassandra/metadata.py

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📝 Walkthrough

Walkthrough

MD5Token.hash_fn now calls md5 with usedforsecurity=False. The function retains its existing digest conversion and absolute-value behavior.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the MD5 compatibility change for FIPS environments.
Description check	✅ Passed	The description explains the change, its purpose, cherry-pick source, and test results; the main required information is present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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