"unistd.h" C header is present on POSIX systems (MacOS and Linux), but not on Windows, therefore you can't build a wheel for Windows.

I took a look and "statesampler_fast.pyx" uses "unistd.h" only because of the `usleep` function. Unless we use C++ which offers [1], the solution would be to search for the equivalent of `usleep` that works on Windows.

[1] https://en.cppreference.com/w/cpp/thread/sleep_for