Run `mix credo` on `GitHub Actions` for Code Consistency 😍

[nelsonic]

Context

We have used 3^rd party code quality badges e.g. CodeClimate in the past.
But haven't applied them to our Elixir projects ... until now! 🤷‍♂️

Example

while reading: https://github.com/cesium/safira discovered via @ruilopesm & @nelsonmestevao 🫶

we see they have the following badge: prominently displayed:

The action is: /cesium/safira/.github/workflows/style.yml

Note: we are using credo in several projects e.g: mvp
just not running the mix task on GitHub Actions or displaying a badge for "Code Quality".

Todo ✅

• Document the setup steps in a code-style.md file in this (/learn-elixir) repo. 📝
  • Create PR here in /learn-elixir 🆕
• Add it to at least one repo, e.g: fields 🌻
• Run the mix credo --all --strict on localhost to ensure it passes; 💻
  • Make any necessary changes. 🛠️
• Add a flat-square badge to the repo. 🏷️
• Create PR in the repo where the style.yml task is being added.
• Submit for review. 👀

[nelsonic]

https://github.com/rrrene/credo