fixed bug in cv composer

cdplib/ml_validation/CVComposer.py

@@ -17,7 +17,7 @@ from cdplib.log import Log
 CVType = NewType("CVType", Iterable[Tuple[List]])
 
 DataSetType = NewType("DataSetType",
-                      Union[pd.DataFrame, pd.Sereis, np.ndarray, List])
+                      Union[pd.DataFrame, pd.Series, np.ndarray, List])
 
 
 class CVComposer: