Fix QA pipeline on Windows
# What does this PR do?

As reported on the [forum](https://discuss.huggingface.co/t/pipeline-example-in-the-doc-throws-an-error-question-answering/2632), there is a problem in the current pipeline on Windows. The problem's root is that numpy int arrays have a different default on Linux and Windows, the current snippet:
```
import numpy as np
x = np.array([1, 2, 3])
x.dtype
```
will print `dtype('int64')` on Linux/MacOS but `dtype('int32')` on Windows. So this means that just doing `torch.tensor(some_numpy_array)` may result in a tensor of dtype `int32` which PyTorch does not like. For future reference, the error:
```
Expected tensor for argument #1 'xxx' to have scalar type Long; but got torch.IntTensor instead
```
is usually a clear indicator of this behavior happening.

The PR fixes the QA pipeline by casting the tensors to long if they have the int type.