Fix a bug in run_qa_no_trainer.py
Author: dreamgonfly
Pull request: yes

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Fixes a bug in run_qa_no_trainer.py.
In the code, eval_metric dictionary generated from [squad metric](https://huggingface.co/metrics/squad) doesn't have 'exact' key.
KeyError: 'exact' raised during execution.


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Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_16867). All of your documentation changes will be reflected on that endpoint.

Hi @dreamgonfly I have a more comprehensive PR that fixes this issue. Turns out that saving of the metrics is tricky, because the unit tests (which fail in your case) actually use SQuAD v2 metric and they have a different name for the exact matching score. Naturally, you were running this code from the command line and it was using the SQuAD v1 metric. This is why your tests are failing, but the command line results are fine (it took me a few hours of head scratching to figure this out):
https://github.com/huggingface/transformers/pull/16958