The --all command from the devguide fails on Windows.

--all should only enable unixy_check on Unixy platforms.

Linked PRs

• gh-105091: stable_abi.py: Remove "Unixy" check from --all on other platforms #105092
• [3.12] gh-105091: stable_abi.py: Remove "Unixy" check from --all on other platforms (GH-105092) #105133