pre-commit application is not available

I just git cloned the https://github.com/dwyl/elixir-auth-github project and ran `mix deps.get` followed by `mix test` and got the following warning/error:


```
You have configured application :pre_commit in your configuration file,
but the application is not available.

This usually means one of:

1. You have not added the application as a dependency in a mix.exs file.

2. You are configuring an application that does not really exist.

Please ensure :pre_commit exists or remove the configuration.
```

We may need to add additional setup instructions to this project. 💭

まず、新しい clone で報告された `mix deps.get` に続く `mix test` コマンドを再現し、その後、プロジェクト設定を調べて `:pre_commit` アプリケーションと関連するセットアップ手順を確認します。警告が解消されるか、新しいユーザー向けに必要なセットアップが明確に文書化されれば完了です。

索引モデルが issue の本文から書いたものです。