fix: include typing marker in built distributions

[Shubham-Padkonde]

Description

Use the import package name redshift_connector as the package_data key. Setuptools expects a package name here, so the distribution-style redshift-connector key does not include py.typed on older builders.

Motivation and Context

Fixes #257. Wheels built without the marker prevent downstream type checkers from using the driver's inline annotations, despite the earlier typing support in #224.

Testing

• Built clean source copies with setuptools 68.2.2 using setup.py sdist bdist_wheel: the original wheel omits py.typed; the patched wheel includes it. Both retain the certificate file.
• Repeated the patched build with setuptools 84.0.0: the marker and certificate are present.
• Python 3.10 unit suite: 2,040 passed, 13 skipped.
• Ran the repository pre-commit hooks. Black formatted the changed entry. The isort hook scans the entire repository and found pre-existing import ordering differences, which are excluded from this PR. Mypy reports two setup.py argument-type errors with its current setuptools stubs; the same errors reproduce on the unmodified setup.py.

No live Redshift integration tests were run; this change affects package contents only.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• Local run of the ./build.sh build command succeeds
• Code changes have been run against the repository's pre-commit hooks
• Commit messages follow Conventional Commit Specification
• I have read the README document
• I have added tests to cover my changes (validated actual clean wheel contents as described above)
• I have run all unit tests using pytest test/unit and they are passing