test_pyrepl leaks references about cpython

[ambv]

thanks for the super quick investigation, Victor

[vstinner]

The problem comes from self.old_sigwinch = signal.signal(signal.SIGWINCH, self.__sigwinch) in UnixConsole.prepare(). The test doesn't call console.restore().

[vstinner]

Python 3.13 is also affected. Example:

$ ./python -m test test_pyrepl -u all -R 3:3 -m test_simple_addition
(...)
test_pyrepl leaked [851, 851, 851] references, sum=2553
test_pyrepl leaked [289, 289, 289] memory blocks, sum=867

[ambv]

Will backport.