feat: add py.typed marker for PEP 561 compliance

[kalichiruvelli-art]

Summary

Adds an empty py.typed marker file to the flaml/ package directory as specified by PEP 561.

Problem

Type checkers (Pyright, Pylance, mypy) treat flaml as untyped because there is no py.typed marker, causing warnings like:
Stub file not found for "flaml" (reportMissingTypeStubs)

Fix

• Add an empty flaml/py.typed marker file (zero bytes, no logic changes)
• • Add [tool.setuptools.package-data] entry in pyproject.toml so the file is included in the built distribution
    No logic changes, no new dependencies.

[Copilot]

Pull request overview

This PR aims to make flaml PEP 561-compliant so type checkers (Pyright/Pylance/mypy) recognize it as a typed package by shipping a py.typed marker in the distribution.

Changes:

• Add flaml/py.typed marker file.
• Add a pyproject.toml entry intended to include py.typed as package data during packaging.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pyproject.toml	Adds setuptools package-data config for shipping flaml/py.typed.
flaml/py.typed	Adds the PEP 561 marker file to the package.

[Copilot]

This [tool.setuptools.package-data] entry may not be applied in the current release/build pipeline, which runs python setup.py sdist bdist_wheel (see .github/workflows/CD.yml). Since setup.py currently only sets package_data for flaml.default, the built wheel may still omit flaml/py.typed, defeating the PEP 561 marker. Consider adding py.typed to package_data in setup.py (or switching packaging to a PEP 517/pyproject-based setuptools config) to ensure it is included in sdists/wheels.

[kalichiruvelli-art]

@microsoft-github-policy-service agree