Use of depreciated class SafeChildWatcher in capture.py

[emmseth]

Lines 202 - 203 of capture.py use SafeChildWatcher in the set_event_loop() method. However, this is currently depreciated and set to be fully removed for Python 3.14. Starting to look for another solution early could save some trouble down the line.

I've been having difficulty finding a good solution, as ThreadedChildWatcher appears to still be recommended for this functionality for Unix os in the asyncio documentation.