fix wheel/sdist build

[lgarrison]

The release pipeline is all kinds of broken! Both sdist and wheel builds are failing.

The sdist fix should be a quick one. The wheel build is failing on MacOS with a delocation error:

  delocate.libsana.DelocationError: Library dependencies do not satisfy target MacOS version 11.0:
  /private/var/folders/y6/nj790rtn62lfktb1sh__79hc0000gn/T/tmpnfrjuj62/wheel/jax_finufft/.dylibs/libfftw3f.3.dylib has a minimum target of 14.0
  /private/var/folders/y6/nj790rtn62lfktb1sh__79hc0000gn/T/tmpnfrjuj62/wheel/jax_finufft/.dylibs/libfftw3.3.dylib has a minimum target of 14.0
  Set the environment variable 'MACOSX_DEPLOYMENT_TARGET=14.0' to update minimum supported macOS for this wheel.

I think this is because we're brew-installing fftw, which is installing it for the current runner (macos-14) rather than the target platform (11.0). cibuildwheel mentions this pitfall: https://cibuildwheel.pypa.io/en/stable/faq/#macos-library-dependencies-do-not-satisfy-target-macos

finufft is now smart enough to fetch and build its own fftw through CPM, so if we're lucky, simply removing the brew install will be enough to fix this.

[lgarrison]

FFTW is failing to compile:

2025-06-06T21:30:45.5680980Z   /Users/runner/work/jax-finufft/jax-finufft/build/cp310-cp310-macosx_11_0_arm64/_deps/fftw3-src/simd-support/x86-cpuid.h:137:16: error: invalid output constraint '+a' in asm
2025-06-06T21:30:45.5681060Z                : "+a" (*eax), "+r" (*ebx), "+c" (*ecx), "+d" (*edx));

etc.

But finufft appears to be doing what we're trying to do, so let's try copying their config.

[lgarrison]

Well, now the error has moved to libomp, which we're brew-installing:

  /private/var/folders/y6/nj790rtn62lfktb1sh__79hc0000gn/T/tmpl6vtqjie/wheel/jax_finufft/.dylibs/libomp.dylib has a minimum target of 14.0
  Set the environment variable 'MACOSX_DEPLOYMENT_TARGET=14.0' to update minimum supported macOS for this wheel.

Our options at this point may be (1) disabling libomp for old macos wheels, (2) not building wheels for old macos (I think we could do >=13 for Intel and >=14 for ARM via GH Actions), or (3) trying to set up builds using an old macos image on Jenkins.

I'm inclined to go with (2), unless @dfm has any ideas?

[dfm]

Let me take a look later this weekend!