python.nvim stable release

After the initial release of python.nvim I have been using and refining this plugin to a point where I feel its ready to be called "stable".

• documentation
• tests
• sub commands
• linting
• ci

Come together to mark what I considering python.nvim's first release!

I hope you enjoy this plugin and it improves your python experience in neovim like it does for me ❤️.