[docs] incorrect `BlockingIOError` pre-condition in versionchanged note of `hashlib.file_digest()`

[moreati]

hashlib.file_digest() now raises BlockingIOError if the file object is non-blocking and a syscall returns EWOULDBLOCK. This is incorrectly described in one spot, the versionchanged note.

First discussion in #122183 (comment), original issue #122179, original 3.13 backport #132787.

Linked PRs

• gh-139495: Fix hashlib.file_digest() versionchanged description of BlockingIOError #139496
• [3.14] gh-139495: Fix hashlib.file_digest() versionchanged description of BlockingIOError (GH-139496) #139522
• [3.13] gh-139495: Fix hashlib.file_digest() versionchanged description of BlockingIOError (GH-139496) #139528