Title: setup.py fails on CPU-only machines due to unhandled PermissionError

[belassiter]

When installing on a Linux system without the NVIDIA CUDA Toolkit, the setup.py script fails.

The cuda_toolkit_available function calls subprocess.call(["nvcc"]). On some systems, this raises a PermissionError: [Errno 13] Permission denied instead of the expected FileNotFoundError.

Because PermissionError is not caught, the script crashes, preventing installation on CPU-only machines. The try...except block should also catch PermissionError.

[belassiter]

Note: Gemini told me all of this. But its edits to setup.py fixed the problem, so I figured I would report it.