Error when getting the long-t5 model
### System Info

When I get the relevant pipline or the corresponding model and tokenizer from this page, I get the `KeyError: 'longt5'`


### Who can help?

@patrickvonplaten 

### Information

- [X] The official example scripts
- [ ] My own modified scripts

### Tasks

- [X] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

https://huggingface.co/google/long-t5-tglobal-base
my code:
```
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM

tokenizer = AutoTokenizer.from_pretrained("google/long-t5-tglobal-base")
model = AutoModelForSeq2SeqLM.from_pretrained("google/long-t5-tglobal-base")
```
Full error output:
```
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<command-440662132347528> in <module>
      1 from transformers import AutoTokenizer, AutoModelForSeq2SeqLM
      2 
----> 3 tokenizer = AutoTokenizer.from_pretrained("google/long-t5-tglobal-base")
      4 model = AutoModelForSeq2SeqLM.from_pretrained("google/long-t5-tglobal-base")

/databricks/python/lib/python3.8/site-packages/transformers/models/auto/tokenization_auto.py in from_pretrained(cls, pretrained_model_name_or_path, *inputs, **kwargs)
    400     tokenizer_config = get_tokenizer_config("bert-base-uncased")
    401     # This model does not have a tokenizer config so the result will be an empty dict.
--> 402     tokenizer_config = get_tokenizer_config("xlm-roberta-base")
    403 
    404     # Save a pretrained tokenizer locally and you can reload its config

/databricks/python/lib/python3.8/site-packages/transformers/models/auto/configuration_auto.py in from_pretrained(cls, pretrained_model_name_or_path, **kwargs)
    430         ("unispeech", "UniSpeech"),
    431         ("unispeech-sat", "UniSpeechSat"),
--> 432         ("van", "VAN"),
    433         ("videomae", "VideoMAE"),
    434         ("vilt", "ViLT"),

KeyError: 'longt5'
```
Any kind of help is appreciated!

### Expected behavior

Correct import of models and corresponding piplines
Hi, what `transformers` version are you using?<|||||>> Hi, what `transformers` version are you using?

I am using `transformers==4.24.0`<|||||>@ArthurZucker could you take a look here? <|||||>Not really able to reproduce the code for now, but will have a look! I also used `transformers==4.24.0` and the import worked. It was added 6 month ago see [here](https://github.com/huggingface/transformers/pull/16792). Also can confirm that `("longt5", "LongT5"),` is [in the auto config](https://github.com/ArthurZucker/transformers/blob/main/src/transformers/models/auto/configuration_auto.py#L391).<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.