title: joblib.load and pickle.load error "No attribute 'XGBoostLabelEncoder'"
body: <p>I'm trying to load a XBGClassifier model with joblib and pickle.</p>
  <p>When using joblib <code>loaded_model = joblib.load('trained_model.sav')</code> I'm getting the following error: <strong>AttributeError: module 'xgboost.compat' has no attribute 'XGBoostLabelEncoder'</strong></p>
  <p>And with pickle <code>loaded_model = pickle.load(open('trained_model.sav', 'rb'))</code> I get <strong>AttributeError: Can't get attribute 'XGBoostLabelEncoder' on &lt;module 'xgboost.compat' from 'C:\Users\Usuario\Anaconda3\lib\site-packages\xgboost\compat.py'&gt;</strong></p>
  <p>I installed xgboost again but it doesn't work, what might be the issue?</p>