Make `os.scandir` retry on system calls failing with EINTR

Bug report

Bug description:

In a long-running script, I hit:

[…]
  File "/Users/gsnedders/ct.py", line 104, in worker
    with os.scandir(path) as it:
         ~~~~~~~~~~^^^^^^
InterruptedError: [Errno 4] Interrupted system call: '/Users/gsnedders/Library/Containers/com.apple.ScreenTimeWidgetApplication.ScreenTimeWidgetExtension/Data/Library/Application Scripts'

No repro case is provided, because that would require making syscalls fail with EINTR reliably somehow.

PEP 475 (Retry system calls failing with EINTR) implies to me that os.scandir should be retrying, rather than just failing here.

It does appear that os.scandir doesn't always retry, looking at the source:

https://github.com/python/cpython/blob/ae3064608935367c860182dc1b364631082ecdff/Modules/posixmodule.c#L16489

The iterator itself also seems to not retry:

https://github.com/python/cpython/blob/ae3064608935367c860182dc1b364631082ecdff/Modules/posixmodule.c#L16290

CPython versions tested on:

3.13

Operating systems tested on:

macOS

Leggi PEP 475 e l’implementazione collegata di os.scandir in Modules/posixmodule.c, incluso il codice dell’iteratore alle righe indicate. Controlla come vengono gestite le chiamate di sistema che restituiscono EINTR e verifica che os.scandir riprovi invece di sollevare InterruptedError. Il lavoro è completato quando sia la chiamata iniziale sia il comportamento dell’iteratore corrispondono alla politica di ritentativo prevista.