nano /Users/[YOUR-USERNAME]/.composer/auth.json

Before:

{
	"github-oauth": {
		"github.com": "ghp_[YOUR-PERSONAL-ACCESS-TOKEN]"
	}
}

After:

{
	"http-basic": {
	    "github.com": {
	      "username": "[YOUR-USERNAME]",
	      "password": "ghp_[YOUR-PERSONAL-ACCESS-TOKEN]"
	    }
	}
}