Add Python 3.15 and 3.15t to CI wheels workflow

[cclauss]

As recommended at:

• MNT Python 3.15 support scikit-learn#34652 (comment)

@lesteve

[lesteve]

Nice, thanks for the PR!

Because we use cibuildwheel 4.0.0, looks like we need to enable them explicitly or update to 4.2.0 which enables them by default.

I tried the latter option which seems simpler and also numpy-release is already using cibuildwheel 4.2.0 see numpy/numpy-release#62.

[lesteve]

OK the Python 3.11 is failing because it can not install scipy 1.18.1 which probably doesn't support Python 3.11.

Python 3.15 needs to install scipy 1.18.1 which is the only version to have Python 3.15 wheels.

It's probably doable to have something like this in our requirements.txt:

scipy==1.17.1; python_version == "3.11"
scipy==1.18.1; python_version != "3.11"

I am still going to leave the Python 3.15 ones run to see if there is any unexpected issue.

[cclauss]

Please rerun the failing Python 3.15 test. It is difficult to believe that they have a 3.15t image but no 3.15 image!

++ docker run -it -v 'D:\a\scikit-learn-release\scikit-learn-release:C:/mnt' -d winamd64/python:3.15-windowsservercore
Unable to find image 'winamd64/python:3.15-windowsservercore' locally
docker: Error response from daemon: manifest for winamd64/python:3.15-windowsservercore not found: manifest unknown: manifest unknown

[cclauss]

Added:

scipy==1.17.1; python_version == "3.11"
scipy==1.18.1; python_version != "3.11"

in both requirements files.

[lesteve]

Please rerun the failing Python 3.15 test. It is difficult to believe that they have a 3.15t image but no 3.15 image!

So this error is about our additional testing that we do inside a minimal Docker image to make sure we correctly bundle the C++ MSVC runtime and OpenMP DLLs on Windows in the wheel.

The easiest thing to do is to skip it for Python 3.15 since there is no Docker image because Python 3.15 has not been released yet. There is a 3.15-rc image and historically we have been trying to use it between the Python rc and release. IMO it's not worth it since it is quite unlikely that the vendoring of DLL works differently for Python 3.15, so for now, let's just skip this on Python 3.15.

[cclauss]

Nice!

[lesteve]

Let's merge this one, thanks for the PR!