Streamline the homebrew release process

[charlespwd]

Right now the ~gem +~ brew publishing process is manual. We might want to make that automatic when we make releases instead.

For homebrew, shopify/shopify-app-cli uses a Github action: https://github.com/Shopify/shopify-app-cli/blob/master/.github/workflows/release.yml#L43-L48 https://github.com/dawidd6/action-homebrew-bump-formula

[macournoyer]

The pushing to rubygems has been mostly automated.

It does require a manual pumping of the version in the code, then you do have to go to https://shipit.shopify.io/shopify/theme-check/rubygems and click deploy. But that's what shopify-app-cli and other repos are using too

[charlespwd]

Then I'll rename this to be homebrew specific. Good to know :)