gh-139495: Fix `hashlib.file_digest()` versionchanged description of `BlockingIOError` (GH-139496)

* Fix `hashlib.file_digest()` versionchanged description of `BlockingIOError`

The sentence was missing a negation and contradicted the other two
descriptions in the same commit. I believe code behaviour is correct.

* fixup! Fix `hashlib.file_digest()` versionchanged description of `BlockingIOError`

* Remove unncessary NEWS.d entry