setup.cfg - fix [wheel] -> [bdist_wheel]

[wheel] is legacy, [bdist_wheel] is the future. See https://bitbucket.org/pypa/wheel/src/4da780b849affbff98a0defb21ad1f30a94d6f57/wheel/bdist_wheel.py?at=default&fileviewer=file-view-default#bdist_wheel.py-119