fix: pandas df truthiness

[elboy3]

>>> bool(dataset)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
[<ipython-input-9-c57750f91409>](https://localhost:8080/#) in <cell line: 1>()
----> 1 bool(dataset)

[/usr/local/lib/python3.10/dist-packages/pandas/core/generic.py](https://localhost:8080/#) in __nonzero__(self)
   1525     @final
   1526     def __nonzero__(self) -> NoReturn:
-> 1527         raise ValueError(
   1528             f"The truth value of a {type(self).__name__} is ambiguous. "
   1529             "Use a.empty, a.bool(), a.item(), a.any() or a.all()."

ValueError: The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().