fix llvmdev osx64 conda builder

[swap357]

This PR fixes osx64 build for llvmdev conda and wheel builder by setting up macOS sdk compatible to work with conda build on GHA runner.

[sklam]

Can we get the osx wheel tester going with this? It's the best way to test whether the build config changes are ok.

[swap357]

Can we get the osx wheel tester going with this? It's the best way to test whether the build config changes are ok.

the condo package as well as wheel are tested with GHA on this change -
https://github.com/numba/llvmlite/actions/runs/14068772517

[esc]

@swap357 thank you for this. I think in order to test this well, we will need the osx builders for llvmlite and numba.

[esc]

One question and one requested change.

[esc]

@swap357 thank you again, now waiting on the llvmlite builders to become available for review such that I can test the artifacts produced from this workflow in earnest.