BUG: Type Annotations in PythonNode Wrong

[axtimhaus]

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pytask.
• (optional) I have confirmed this bug exists on the main branch of pytask.

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Code Sample, a copy-pastable example

This is the example from the docs https://pytask-dev.readthedocs.io/en/stable/how_to_guides/hashing_inputs_of_tasks.html.

import json
from pathlib import Path
from typing import Annotated
from typing import Any

from deepdiff import DeepHash
from pytask import Product
from pytask import PythonNode


def calculate_hash(x: Any) -> str:
    return DeepHash(x)[x]


node = PythonNode(value={"a": 1, "b": 2}, hash=calculate_hash)


def task_example(
    data: Annotated[dict[str, int], node],
    path: Annotated[Path, Product] = Path("file.txt"),
) -> None:
    path.write_text(json.dumps(data))

Problem description

When I do this example, my type checker complains about the type of the provided hash function.

Type annotation from current master:

pytask/src/_pytask/nodes.py

Line 238 in f18df8f

hash: bool | Callable[[Any], bool] = False

I think bool as return type of the callable makes no sense here.
Running the code works perfectly fine, just the checker complaining.

Expected Output

By looking into the source Callable[[Any], Any] would work (because the result is passed to str()), or a more defined one like Callable[[Any], int | str | bytes] as these are common returns of hash functions.

[tobiasraabe]

Thanks for filing the issue, @axtimhaus! I will have a look soon. I am wondering whether we need the flexibility with the union return type. Maybe I find packages offering similar functionality for inspiration.