[Kwant] Kwant fix for osx-arm64 conda

[Anton Akhmerov via Kwant-discuss]

Hi all,

I was finally able to identify and fix a long-standing issue for Kwant packaged 
via conda on apple silicon. The fix should work with the latest version of 
Kwant (1.5) and latest release of python-mumps.

Happy Kwanting,
Anton