Fix SequenceLengthSimilarity docstring (#659)

Author: fealho

sdmetrics/single_column/statistical/sequence_length_similarity.py

@@ -41,9 +41,9 @@ def compute(real_data: pd.Series, synthetic_data: pd.Series) -> float:
             - Return this score
 
         Args:
-            real_data (Union[numpy.ndarray, pandas.DataFrame]):
+            real_data (pd.Series):
                 The values from the real dataset.
-            synthetic_data (Union[numpy.ndarray, pandas.DataFrame]):
+            synthetic_data (pd.Series):
                 The values from the synthetic dataset.
 
         Returns: