add SF-ETS to models init file

Author: hrzn

darts/models/__init__.py

@@ -22,6 +22,7 @@
 from darts.models.forecasting.regression_ensemble_model import RegressionEnsembleModel
 from darts.models.forecasting.regression_model import RegressionModel
 from darts.models.forecasting.sf_auto_arima import StatsForecastAutoARIMA
+from darts.models.forecasting.sf_ets import StatsForecastETS
 from darts.models.forecasting.tbats import BATS, TBATS
 from darts.models.forecasting.theta import FourTheta, Theta
 from darts.models.forecasting.varima import VARIMA