Fix auxiliary_outputs types in loss
Author: xiuqhou
Pull request: yes
Labels: name: bug

name: run-slow

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This PR fix process of auxiliary_outputs and other returns when `return_dict = False`. `auxiliary_outputs` is not a tuple of returns, it should be processed as an element of return tuple, similar to RT-DETR (https://github.com/huggingface/transformers/blob/main/src/transformers/models/rt_detr/modeling_rt_detr.py#L2137). 

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Comments:
CI errors seem not related to changes. I have pushed code many times and seen different mistakes each run.

Hi @xiuqhou this looks good! You can try to rebase to fix the test issues.

I have one request before we go to final review and merging: Can you add or modify a test for the affected models to check this case, so we don't get a regression in future?

Hi @Rocketknight1 Thanks for reply. Now I can pass CI test.
I have modified `test_model_outputs_equivalence` for Deformable-DETR to check output equivalence for auxiliary and two-stage settings, affected by this PR.

But the same test cannot be added for other models as they cannot pass it now. It is not because of this PR, but because the tuple output and dict output of them have different return sequences for auxiliary and two-stage settings. This problem may also need to be fixed before adding the test. I think code change may be beyond the scope of this PR.

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