sentencepiece version need upgrade
## Environment info

- `transformers` version: 4.11.0.dev0
- Platform: Debian Gnu/Linux
- Python version: 3.9
- PyTorch version (GPU?):
- Tensorflow version (GPU?):
- Using GPU in script?:
- Using distributed or parallel set-up in script?:

### Who can help

- setup: @LysandreJik may be ?

## Information

sentencepiece==0.1.91 does not exist anymore

pip install fails:

```
ERROR: Could not find a version that satisfies the requirement sentencepiece==0.1.91
ERROR: No matching distribution found for sentencepiece==0.1.91
```

## To reproduce

Steps to reproduce the behavior:

1. create a new venv
2. pip install -e .


## Expected behavior

- Need to bump to the latest but minor version change 0.1.96 for transformer's install to work

It just worked fine on a new env. Maybe you need a `pip install --upgrade pip`?<|||||>> It just worked fine on a new env. Maybe you need a `pip install --upgrade pip`?

Yeah indeed, it worked for me too.