Windows multiprocessing spawn error

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While using the multiprocessing library on Windows, I get the following error:

```shell
Traceback (most recent call last):
File "multiprocessing.spawn", line 107, in spawn_main
File "multiprocessing.reduction", line 79, in duplicate
TypeError: DuplicateHandle() argument 2 must be int, not dict
```

The code I'm using is roughly:

```python
with multiprocessing.Pool(
processes=, initializer=, initargs=[, ]
) as pool:
output = pool.map(
,
tqdm(tqdm(>, fh=))
)
```

The use of `tqdm` with a file handler is just so that progress logging can be written to file, and replacing it with an ordinary list yields the same error. The code itself builds and executes just fine on linux and macOS (both Intel and ARM).

I've tried various configurations suggested [here](https://pyoxidizer.readthedocs.io/en/stable/pyoxidizer_packaging_multiprocessing.html) without success. Any insight as to what could be happening? Thanks!

Start by reproducing the Windows multiprocessing failure with the shown Pool example and an ordinary list, then review the linked PyOxidizer multiprocessing packaging guidance. Done means the packaged application can use multiprocessing on Windows without the DuplicateHandle TypeError.

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