fix new name for sparse arguement

Signed-off-by: Xavier Dupre <xadupre@microsoft.com>

tests/xgboost/test_xgboost_pipeline.py

@@ -50,7 +50,7 @@ def transformer_for_column(column):
             if column.dtype in ["bool"]:
                 return "passthrough"
             if column.dtype in ["O"]:
-                return OneHotEncoder(sparse=False)
+                return OneHotEncoder(sparse_output=False)
             raise ValueError()
 
         return ColumnTransformer(