subprocess support #401
Description
When running a subprocess() command in the context of a test case, the settings are not carried over into the subprocess, as it has its own execution context.
While there's low likelihood that this library could or should prevent a non-Python command like subprocess.check_call(["curl", "https://example.com"]), if the subprocess is another Python program, we should attempt to apply the same settings to that Python execution.
See how pytest-cov does this: https://pytest-cov.readthedocs.io/en/stable/subprocess-support.html