fix(ci): make abi3audit step OS-aware (fix Windows wheel-build job)

[jhamon]

Summary

• Replaces hardcoded /tmp/abi3audit-venv/bin/... paths with OS-aware equivalents
• Uses $RUNNER_TEMP instead of /tmp for the venv parent (works on all runner OSes)
• Detects Scripts/ (Windows) vs bin/ (Linux/macOS) for the binary directory
• Fixes exit code 127 failure on x86_64-pc-windows-msvc runners (CI-0060)

Root cause

The abi3audit step (lines 416–422) hardcoded Unix-style paths. On Windows runners:

1. Git Bash maps /tmp to a runner-specific AppData/Local/Temp path, not RUNNER_TEMP
2. Windows venvs place binaries in Scripts/, not bin/

This combination caused "No such file or directory" / exit 127 on every Windows wheel build.

Verification

Release Readiness run on this branch with skip_integration=true:
https://github.com/pinecone-io/python-sdk/actions/runs/25521225781

All wheel build jobs green, including Wheel build (x86_64-pc-windows-msvc). CI-0037's isolation intent (separate venv for abi3audit) is preserved.

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Note

Low Risk
Low risk workflow tweak that only changes how the abi3audit virtualenv is created/invoked; main risk is CI regressions if path detection or $RUNNER_TEMP behaves unexpectedly on some runners.

Overview
Fixes the release-readiness wheel-build job’s abi3audit step to work cross-platform by creating the venv under RUNNER_TEMP and selecting Scripts/ (Windows) vs bin/ (Unix) when invoking pip/python.

This removes hardcoded /tmp/.../bin/... paths, preventing Windows wheel builds from failing with missing executable/path errors while preserving the venv isolation intent.

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