[Typing] `list_tasks` can be made more explicit in return type with `@overload`

[eddiebergman]

By using an @overload, on output_type: Literal["dict", "dataframe"] this can be converted used to give the correct type returned.

openml-python/openml/tasks/functions.py

Lines 129 to 136 in 56895c2

	def list_tasks(
	task_type: Optional[TaskType] = None,
	offset: Optional[int] = None,
	size: Optional[int] = None,
	tag: Optional[str] = None,
	output_format: str = "dict",
	**kwargs,
	) -> Union[Dict, pd.DataFrame]:

• Could be partially done for get_X_and_y, at least for dataframe.