Determine one license

[IvanaGyro]

There are two licenses declared in this project. In LICENSE file, we declared the license as Apache 2.0; in setup.py we declared the licnese as LGPL. Which one is the correct license?

[pcchen]

I would sugget to use Apache 2.0.

[yingjerkao]

I think that was an old license from Uni10. We should all use Apache 2.0.

[yingjerkao]

@IvanaGyro This is resolved?

[IvanaGyro]

Do we need setup_macos.py?

[yingjerkao]

Are we completely moving to condo_build? If so, we can remove setup_macos.py

[IvanaGyro]

We are using scikit-build-core. As #629 (comment) mentioned, users can just call pip install . to install Cytnx on Mac.

[pcchen]

I think the current `'pip install .' is quite good.