add github action 🚀

[ThomasAndrewMacLean]

docs: https://github.com/pgrimaud/action-shopify

This is the github action I use to deploy to shopify.

The secrets have to be added to github => settings => secrets

You need to create a new private app with read and write access to the theme, if you dont have a specific subfolder for your theme use ./ as the theme path.

I use the commented out Build step to build React components that I output in the /assets folder