Broken link error when using the CLIPTokenizerFast class
## Environment info


- `transformers` version: 4.17.0.dev0
- Platform: Linux-5.13.0-30-generic-x86_64-with-glibc2.10
- Python version: 3.8.12
- PyTorch version (GPU?): 1.11.0.dev20220116 (True)
- Tensorflow version (GPU?): not installed (NA)
- Flax version (CPU?/GPU?/TPU?): not installed (NA)
- Jax version: not installed
- JaxLib version: not installed
- Using GPU in script?: <fill in>

### Who can help

Models:
@LysandreJik The model is clip-vit-base-patch16

Library:

- Tokenizers: @SaulLu

## Information
I am suddenly getting the error 
```requests.exceptions.HTTPError: 502 Server Error: Bad Gateway for url: https://huggingface.co/openai/clip-vit-base-patch16/resolve/main/vocab.json``` when trying to use the CLIP tokenizer. 

## To reproduce

Steps to reproduce the behavior:

1. Just execute 
`tokenizer = CLIPTokenizerFast.from_pretrained("openai/clip-vit-base-patch16")`

To get the error message:

``` File "/home/evolvingfungus/miniforge3/envs/tali/lib/python3.8/site-packages/transformers/tokenization_utils_base.py", line 1763, in from_pretrained
    raise err
  File "/home/evolvingfungus/miniforge3/envs/tali/lib/python3.8/site-packages/transformers/tokenization_utils_base.py", line 1724, in from_pretrained
    resolved_vocab_files[file_id] = cached_path(
  File "/home/evolvingfungus/miniforge3/envs/tali/lib/python3.8/site-packages/transformers/file_utils.py", line 1921, in cached_path
    output_path = get_from_cache(
  File "/home/evolvingfungus/miniforge3/envs/tali/lib/python3.8/site-packages/transformers/file_utils.py", line 2125, in get_from_cache
    _raise_for_status(r)
  File "/home/evolvingfungus/miniforge3/envs/tali/lib/python3.8/site-packages/transformers/file_utils.py", line 2052, in _raise_for_status
    request.raise_for_status()
  File "/home/evolvingfungus/miniforge3/envs/tali/lib/python3.8/site-packages/requests/models.py", line 960, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 502 Server Error: Bad Gateway for url: https://huggingface.co/openai/clip-vit-base-patch16/resolve/main/vocab.json
```

## Expected behavior

Normally the snippet should download the CLIP text encoder's vocab and form a tokenizer.

@AntreasAntoniou , I'm so sorry you had this problem. Part of the Hub was briefly unavailable on March 1st around 11pm UTC. I just tested again on my side and your snippet works fine. :smile: 

<|||||>Yeah, it works fine now. Thanks for the response! :)