Your github oauth token for github.com contains invalid characters
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]"
        }
    }
}