don't upload bdist to pypi

In short, bdist (binary distributions) created from a pure python project are universal. They cannot be made to use a platform-specific tag (like linux, windows, macos, etc). This changes the release CI workflow to skip creating/uploading a bdist to PyPI.

This library has a number of dependencies conditionally required per *machine* attributes (like CPU type). But pip (or other python package managers) will not be aware of such conditional dependencies because a bdist do not invoke a dynamic resolution of machine-specific dependencies. Universal bdists only resolve platform-specific dependencies (python version, system OS, etc) which isn't sufficient for this library. Instead, this paradigm is better left to a sdist (source distribution) which carry dependency details per machine-specific attributes in the setup.py file.