Now that we check build dependencies #29132, the numpy in nogil is too old, i.e. 1.24 and we want >=1.25.

I think this may be worth removing this historic nogil build given that a CPython 3.13 free-threaded will happen soonish, maybe a few weeks:

• there is already a free-threaded Numpy wheel in https://anaconda.org/scientific-python-nightly-wheels/numpy/files. Look for 313t (t is the marker for free-threaded)
• there will be soon a free-threaded Scipy wheel: CI: Add workflow to build and upload free-threaded wheels scipy/scipy#20882
• once there is a Scipy wheel, it is up to us to add a CI build for CPython 3.13 free-threaded 😉. Locally it seems like the full test suite passes (at least for me) Add support for Python 3.13 free-threaded build #28978 (comment)

I opened #29191 to remove the nogil CPython 3.9 build.

once there is a Scipy wheel, it is up to us to add a CI build for CPython 3.13 free-threaded 😉.

@lesteve SciPy nightly wheels are available now. Our team for free-threaded CPython at Quansight Labs has bandwidth to help with this kind of task for scikit-learn (wheels, debugging, etc.) over the next months. If you want us to work on adding this new CI job, or contribute to thread-safety fixes or whatever, please don't hesitate to ask.

Yeah I have seen this, this is great! I think it will be more efficient if I add the CI job, because I am familiar with scikit-learn CI quirks, but I definitely will ask you or Nathan when needed.

FYI I opened a CPython 3.13 free-threaded WIP PR in joblib as well recently joblib/joblib#1589