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

Read PEP 475 and the linked os.scandir implementation in Modules/posixmodule.c, including the iterator code at the referenced lines. Check how system calls returning EINTR are handled and verify that os.scandir retries instead of raising InterruptedError. Done means both the initial call and iterator behavior match the intended retry policy.