Categorical column after sequence_index column

[fealho]

Currently, if a dataset contains a categorical column immediately after the sequence_index column the fit breaks with the error TypeError: cannot perform reduce with flexible type. Below is an example that reproduces the issue:

from sdv.demo import load_timeseries_demo
from sdv.timeseries import PAR
import pandas as pd

data = load_timeseries_demo()
data.insert(loc=2, column="Categorical", value="a","b"*(data.shape0//2))
print(data)

model = PAR(
    entity_columns = 'Symbol',
    context_columns = 'MarketCap', 'Sector', 'Industry',
    sequence_index='Date'
)

model.fit(data)