"OT" is present in other datasets than ETT

[marcopeix]

Loading long horizon datasets other than ETT also have the "OT" unique_id.

from datasetsforecast.long_horizon import LongHorizon
Y_df, _, _ = LongHorizon.load(directory='./', group='ECL')
Y_df["unique_id"].unique()

Output:

array(['0', '1', '10', '100', '101', '102', '103', '104', '105', '106',
       '107', '108', '109', '11', '110', '111', '112', '113', '114',
       '115', '116', '117', '118', '119', '12', '120', '121', '122',
...
       '52', '53', '54', '55', '56', '57', '58', '59', '6', '60', '61',
       '62', '63', '64', '65', '66', '67', '68', '69', '7', '70', '71',
       '72', '73', '74', '75', '76', '77', '78', '79', '8', '80', '81',
       '82', '83', '84', '85', '86', '87', '88', '89', '9', '90', '91',
       '92', '93', '94', '95', '96', '97', '98', '99', 'OT'], dtype=object)