[BUG]: PySR randomly hangs during regression on macOS

### What happened? Whenever I'm running regression, suddenly PySR would freeze with 0% CPU usage. If I press enter on my keyboard a few times, it resumes. This will happen entirely randomly, sometimes immediately, sometimes after 1h of regression. It goes away if I set `input_stream='devnull'`, similar to #832. ### Version Python 3.13.3, PySR 1.5.9 ### Operating System macOS ### Package Manager uv 0.9.14 ### Interface Directly running the script via: - Built-in Terminal app - iTerm - Ghostty ### Extra Info _No response_