Fix `SequenceLengthSimilarity` docstrings

[fealho]

Error Description

The docstrings for SequenceLengthSimilarity include the following:

SDMetrics/sdmetrics/timeseries/sequence_length_similarity.py

Lines 43 to 47 in 6bec051

	Args:
	real_data (Union[numpy.ndarray, pandas.DataFrame]):
	The values from the real dataset.
	synthetic_data (Union[numpy.ndarray, pandas.DataFrame]):
	The values from the synthetic dataset.

The type hints for the real and synthetic data parameters are incorrect. They should be pd.Series, not Union[numpy.ndarray, pandas.DataFrame].