Fix compatibility with pytest >= 9.1

[hrnciar]

Summary

pytest 9.1.0 (gh#pytest-dev/pytest#3697) now captures log records from non-propagating loggers, causing uvicorn.access records to appear in caplog.record_tuples. Filter to only httpx2 records in assertions.

Assisted-by: Claude Opus 4.6

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}

[codspeed-hq]

Merging this PR will not alter performance

✅ 15 untouched benchmarks
⏩ 7 skipped benchmarks¹

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_{Comparing hrnciar:patch-1 (c1f50ac) with main (70fac53)}

Footnotes

1. 7 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩