AttributeError: 'IntegerArray' object has no attribute 'size'

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Reproducible example

With pandas==0.25.3

import pandas as pd
from rectools.dataset import IdMap

user_id_map = IdMap.from_values(pd.array([1, 2], dtype=pd.Int32Dtype()))
user_id_map.size
# AttributeError: 'IntegerArray' object has no attribute 'size'

Issue description

The issue seems to be affecting not only pandas==0.25.3, but also pandas==1.0.x (didn't check it thoroughly) There is no such problem with version pandas==1.1.0 and higher

Expected behaviour

Accessing size of IdMap with IntegerArray type doesn't throw an AttributeError