fix bf16 issue in text classification pipeline
Author: chujiezheng
Pull request: yes

# What does this PR do?

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Fixes # (issue)


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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- [ ] Did you write any new necessary tests?


## Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
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Models:

- text models: @ArthurZucker and @younesbelkada
- vision models: @amyeroberts
- speech models: @sanchit-gandhi
- graph models: @clefourrier

Library:

- flax: @sanchit-gandhi
- generate: @gante
- pipelines: @Narsil
- tensorflow: @gante and @Rocketknight1
- tokenizers: @ArthurZucker
- trainer: @muellerzr and @pacman100

Integrations:

- deepspeed: HF Trainer/Accelerate: @pacman100
- ray/raytune: @richardliaw, @amogkam
- Big Model Inference: @SunMarc
- quantization (bitsandbytes, autogpt): @SunMarc and @younesbelkada

Documentation: @stevhliu and @MKhalusova

HF projects:

- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Maintained examples (not research project or legacy):

- Flax: @sanchit-gandhi
- PyTorch: See Models above and tag the person corresponding to the modality of the example.
- TensorFlow: @Rocketknight1

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Comments:
@amyeroberts Hi, this is the new PR I mentioned in https://github.com/huggingface/transformers/pull/30518

@amyeroberts Hello, I have fixed the bugs. The failing CI tests seem about tf or flax, but I guess they are unrelated to this PR?

Hi, I synced with the upstream changes, but the failed tests remain.

@amyeroberts Hi, could you help check the PR? I think this PR is quite simple. It can also facilitate many use cases as the bf16-based classifiers are becoming popular.

Hi @chujiezheng, 

the PR itself all looks good, but there's some outstanding tests which are still failing which need to be resolved before we can merge. When you're merging in `main`, is your `main` branch in-sync with the upstream? 

Yes, I did it just a few hours ago. You can notice the sync in the commits.

@chujiezheng It's very odd. The tests are failing are ones which were failing about two weeks ago and have been resolved. I can see that there's merge commits in the history, although from this I'm not sure if it's possible to tell from which commit in `main` that the merge is happening. 

Could you try a rebase: 
* Pulling the latest changes from the hugging face `main` branch: `git fetch upstream main`
* Go onto the feature branch on your fork `git checkout main`
* Rebase the changes `git rebase upstream/main`
* Force push the changes `git push -f`

The issue still exists...

@chujiezheng Hmm, how odd 🤔 Thanks for trying the rebase. OK, as these tests aren't related to the pipeline, I'm going to forcibly merge. Thanks for your patience and for adding this!