fix: TextIteratorStreamer cannot work with pipeline
Author: yuanwu2017
Pull request: yes

Deepcopying the TextIteratorStreamer object causes the exception.

# What does this PR do?
Fixes #23552 


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Comments:
_The documentation is not available anymore as the PR was closed or merged._

@sgugger , pls help review, thx.

@sywangyi 

@gante Please help to review.

I ran into the same issue and also had another issue about a week ago (which I don't remember now) that was also related to the deepcopy operation. If the sole purpose of the deep copy is to allow calls to `pop` without modifying the dictionary, then shouldn't a shallow copy do?

@gante  We used the transformers pipeline with TextIteratorStreamer for chatbot, but it raised the  deepcopy exception. Can you help to check the issue and review the PR?
Thanks a lot.

@gante is on vacation, please be patient until he comes back :-)
Also cc @Narsil 

> @gante is on vacation, please be patient until he comes back :-) Also cc @Narsil

Got it. Thanks.

Do I need to fix these test failures which are not related with this patch? @gante 

@yuanwu2017 to get rid of the CI errors, please rebase the PR. It is a hard requirement -- LMK if you need instructions to do so :) 

@amyeroberts see the [issue here](https://github.com/huggingface/transformers/issues/23785), which explains why this copy is not needed :)

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_23641). All of your documentation changes will be reflected on that endpoint.