GitHub - URL could not be accessed: HTTP/1.1 400 Bad Request

You have to update your auth.json file. Please go to Settings > Developer settings > Personal access tokens (Direct URL: https://github.com/settings/tokens) page and generate a new token and copy the token string then enable sso and authorise with your private organisation. Update your auth.json like below format.

{
  "http-basic": {
    "github.com": {
        "username": "<YOUR-USERNAME>",
        "password": "<NEW_TOKEN>"
    }
  }
}