refactor(python): Avoid unnecessary cast in Series constructor

[stinodego]

By requiring an exact dtype match we could end up in this branch when it's not required. Example:

from datetime import datetime
import polars as pl

df = pl.DataFrame({"a": [[datetime(1990, 1, 1)]]}, schema={"a": pl.List(pl.Datetime)})

We should just use the equality operator here.