Add missing types to decorators.base

[Viicos]

The usage of a TypeVar seems more appropriate to me here

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[uranusjr]

Not sure if you can do this, CI will tell.

[Viicos]

If we use a TypeVar bound to the variables listed in my comment below, we could maybe use the following instead:
return_value: Dataset | list | dict = super().execute(context)

[Viicos]

Fails at airflow/decorators/base.py:256: error: Incompatible return value type (got "Dict[Any, Any]", expected "RV") [return-value]
Maybe we could use a TypeVar bound to Dataset, list or dict?

[uranusjr]

I have a different thought. Why do we need to return return_value from _handle_output at all? The value is entirely unmodified. Instead of wristling with types, we could simply remove the return value.

[Viicos]

I have a different thought. Why do we need to return return_value from _handle_output at all? The value is entirely unmodified. Instead of wristling with types, we could simply remove the return value.

This is purely to improve types, but is not required as airflow isn't using mypy --strict anyway

[uranusjr]

So my point is, we can make the improvement moot by slightly changing how the code is written (without changing functionalities)

[Viicos]

Sure I can revert this part to Any if necessary ;)

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