ImportError: cannot import name 'CpmTokenizer' from 'transformers'
Author: Biaocsu
Pull request: no

```
nvidia-smi
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 440.118.02   Driver Version: 440.118.02   CUDA Version: 10.2     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  Tesla T4            Off  | 00000000:21:01.0 Off |                    0 |
| N/A   84C    P0    61W /  70W |   8162MiB / 15109MiB |     99%      Default |
+-------------------------------+----------------------+----------------------+
|   1  Tesla T4            Off  | 00000000:21:02.0 Off |                    0 |
| N/A   27C    P8     9W /  70W |     11MiB / 15109MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   2  Tesla T4            Off  | 00000000:21:03.0 Off |                    0 |
| N/A   28C    P8     9W /  70W |     11MiB / 15109MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   3  Tesla T4            Off  | 00000000:21:04.0 Off |                    0 |
| N/A   27C    P8    11W /  70W |     11MiB / 15109MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID   Type   Process name                             Usage      |
|=============================================================================|
|    0     14274      C   python                                      8151MiB |
+-----------------------------------------------------------------------------+
```

```
nvcc -V
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2019 NVIDIA Corporation
Built on Wed_Oct_23_19:24:38_PDT_2019
Cuda compilation tools, release 10.2, V10.2.89
```
```
torch == 1.9.0
transformers == 4.15.0
```
```
Python 3.9.7 (default, Sep 16 2021, 13:09:58)
[GCC 7.5.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from transformers import CpmTokenizer
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'CpmTokenizer' from 'transformers' (/root/anaconda3/lib/python3.9/site-packages/transformers/__init__.py)
>>>

```


Comments:
Probably `sentencepiece` is not installed. `CpmTokenizer` depends on `sentencepiece`, so make sure you have `sentencepiece` installed. You could install it using:
`pip install sentencepiece`

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/master/CONTRIBUTING.md) are likely to be ignored.