Processing does not stop when pressing Ctrl-C

[miltondp]

If I open ipython and run CCC with some data, and I want to stop the computation for some reason, I can press Ctrl+C repeatedly to do that, but the background process does not stop. The only way to stop it is to forcibly terminate the ipython process.

[miltondp]

The latest release of ccc-coef seems to have fixed this problem. At least it works with Python 3.12. If we confirm it works as expected with Python 3.11 and 3.10, we should probably close this issue. @haoyu-zc what do you think?