Publish to PyPI #42

Please publish to PyPI so gcpdiag can be installed with pip (or pipx), and so that the community can build distro packages out of it (homebrew, AUR, other linux distros).

Reasoning:
Current installation instructions suggest installing this tool with curl. A more sophisticated distribution method would be to enable distros to build their own packaging, but for that a base requirement is for this tool being able to publish to PyPI (so it follows common python packaging standards).

Packaging tools (like Homebrew) make it easier to package up tools written in python if it's install-able through PyPI.