Fix QA argument handler

[LysandreJik]

The QA argument handler does not handle multiple sequences at a time anymore. This was not tested, so I added it to the tests.

Fix #8759

To test it out run the following on master:

from transformers import pipeline

nlp = pipeline("question-answering")

context = r"""
Extractive Question Answering is the task of extracting an answer from a text given a question. An example of a
question answering dataset is the SQuAD dataset, which is entirely based on that task. If you would like to fine-tune
a model on a SQuAD task, you may leverage the `run_squad.py`.
"""

print(
    nlp(
        question=["What is extractive question answering?", "What is a good example of a question answering dataset?"],
        context=[context, context],
    )
)

[LysandreJik]

The errors are due to connection errors.