Modernize build for Python 3.10+/3.12 and NumPy 2

[homfunc]

This PR modernizes the Python packaging/build for SPAMS to work out-of-the-box with Python 3.10+ (incl. 3.12) and NumPy 2.

Key changes:

• Switch to explicit PEP 517 backend (setuptools.build_meta) and prefer NumPy 2 in build isolation
• Remove distutils/numpy.distutils usage (Python 3.12 compatibility)
• Vendor SWIG 4.2.0 generated wrappers (removes imp usage; fixes NumPy 2 / NPY_NO_DEPRECATED_API compatibility)
• Build extension as spams_wrap._spams_wrap to match generated imports
• Replace pkg_resources version lookup with importlib.metadata
• Document OpenBLAS/OpenMP warning and add build-time toggle (SPAMS_DISABLE_OPENMP / SPAMS_USE_OPENMP)

Notes:

• The OpenBLAS OpenMP warning is upstream OpenBLAS behavior when calling a non-OpenMP OpenBLAS from OpenMP regions; README includes mitigations.

Co-Authored-By: Warp agent@warp.dev

[samuelstjean]

There is alot of things in there, so did you re-generate the swig wrappers or edit the cpp file directly ?

[homfunc]

There are a lot of things - apologies for that. I regenerated the swig wrapper and there is another PR in spams-devel: spams-devel update SWIG for Python 3.12+ and NumPy 2.

The driver was mainly to support NumPy 2 but I figured that updating the SWIG sources was the best idea.

[samuelstjean]

No it is a great idea, it's just I realised I also updated the wrappers on my side to swig 4.3.0 (here it says it's 4.2.0) and also updated the build system to use meson. While the meson part is a big change as it dumps setup.py in the process but makes it far easier to find any blas implementation, just changing the wrapper is easy enough indeed.