tuning: fix thread counts #2551

Job	Run time
Build sdist	23s
Build wheels for x86_64 on ubuntu-22.04	4m 34s
Build wheels for x64 on windows-latest	5m 50s
Build wheels for aarch64 on macos-14	5m 24s
Build wheels for aarch64 on ubuntu-24.04-arm	5m 2s
Publish to INERTIAL PyPI	0s
Publish to PyPI	0s
	21m 13s

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