Wrong error code value for SumUpSDKError

```
SumUpSDK.login(withToken: "dummy-access-token") { (success: Bool, error: Error?) in
  if ((error as NSError?)?.code == SumUpSDKError.invalidAccessToken.rawValue) {
    print("Invalid token")
  } else {
    print("Unknown error")
   }
 }
```

Would output "Unknown error" as the error code value is actually 20 and SumUpSDKError.invalidAccessToken.rawValue is 54