Fix building with Cython3

[arcondello]

Closes #20. Turns out that's not actually an ARM error, but rather a Cython3 one.

I have tested this change with both Cython 0.29.36 and Cython 3.0.0

[JunkyByte]

Can confirm it builds successfully on Cython 3 and Cython 0.29.36 on a M2 Macbook, thanks!

[arcondello]

@Penlect , any chance you could take a look at this one?

[Penlect]

Thanks guys for investigating this. I don't have any Apple hardware myself unfortunately. I need to build new wheels for this, but I noticed that the CI-job fails in its current form. I will try to take a look at this during the weekend.

[arcondello]

Thanks!

[arcondello]

Hi @Penlect sorry to ping you again - I am sure you have other stuff on your plate. Any chance for an update? Anything I can help with?

[Penlect]

Hi, sorry, yeah I failed to figure out why the CI-job is failing for macos-11:

    OSError: [Errno 66] Directory not empty: '/Users/runner/work/rectangle-packer/rectangle-packer/.eggs/Cython-3.0.2-py3.9-macosx-10.9-x86_64.egg/Cython-3.0.2.dist-info' -> '/Users/runner/work/rectangle-packer/rectangle-packer/.eggs/Cython-3.0.2-py3.9-macosx-10.9-x86_64.egg/EGG-INFO'
    error: subprocess-exited-with-error

and this is basically blocking me from uploading new wheels.

[arcondello]

@Penlect seems to be cython/cython#5568, I could open a PR upper bounding the Cython version or could just wait for that to resolve.