MINOR: [Python] Array.from_buffers accepts None buffers

[robsdedude]

Rationale for this change

Fix the docs. It seems this is a feature and not just happens to work as the code a little below even has an explicit comment:

arrow/python/pyarrow/array.pxi

Line 1347 in 0dfae70

# None will produce a null buffer pointer

What changes are included in this PR?

Document that Array.from_buffers takes a list[Buffer | None] instead of strictly list[Buffer].

Are these changes tested?

not applicable

Are there any user-facing changes?

Yes, but not in an API sense :)

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[robsdedude]

Then could you also rename the pull request title in the following format?

I can in fact not... I think this classifies as a minor change, but I seem to lack permissions to rename my own PR... The button for is isn't showing. Must be a GH thing.

[AlenkaF]

I think this change is OK and would also update the DictionaryArray method docstrings. cc @raulcd what do you think?

[raulcd]

This makes sense to me, even though this will probably be reworked as part of the adding type hints initiative that @rok is leading.
@rok does this look good to you?

[robsdedude]

I think this change is OK and would also update the DictionaryArray method docstrings.

@AlenkaF would you prefer a separate PR or should I extend this one?

[AlenkaF]

Please, extend this one.

[robsdedude]

Done. While at it, I also saw that RunEndEncodedArray might need updating?