GH-49831: [Python] Withhold py.typed from the wheel until stubs are complete

[rok]

Rationale for this change

Since 24.0, pyarrow ships a py.typed marker while the type stubs are still incomplete. This makes type checkers trust the partial stubs and report false errors in downstream code (e.g. Module has no attribute "all" for pyarrow.compute). See #49831.

What changes are included in this PR?

This excludes pyarrow/py.typed from the built wheel via wheel.exclude.

Are these changes tested?

Verified on locally installed wheel with py.typed absent mypy ignores the bundled stubs.

Are there any user-facing changes?

Type checkers no longer pick up pyarrow's incomplete stubs.

• GitHub Issue: [Python] type checkers broken for pyarrow.compute and other sub-modules since PyArrow 24.0+ #49831

[github-actions]

⚠️ GitHub issue #49831 has been automatically assigned in GitHub to PR creator.

[Copilot]

Pull request overview

This PR aims to prevent downstream type checkers from trusting PyArrow’s currently-incomplete bundled type stubs by withholding the PEP 561 py.typed marker from the built wheel (per GH-49831), while keeping stubs and py.typed in-tree for ongoing CI/type-checking work.

Changes:

• Configure the wheel build to exclude pyarrow/py.typed via wheel.exclude.
• Add explanatory comments documenting the rationale and removal TODO.

[dangotbanned]

@rok I strongly recommend excluding the entire directory.

This is all that is in there? 🤨

arrow/python/pyarrow-stubs/pyarrow/__init__.pyi

Lines 24 to 29 in 4fce185

	from typing import Any
	# TODO(GH-48970): remove __getattr__ before release as this
	# will annotate non-existing attributes as Any.
	# https://github.com/apache/arrow/issues/48970
	def __getattr__(name: str) -> Any: ...

We've been pinning pyarrow<24 and the errors we see in (narwhals-dev/narwhals#3560) will still be there for type checkers that aren't mypy 😔