ModuleNotFoundError: No module named 'dgl.contrib'

## 🐛 Bug

## To Reproduce

Steps to reproduce the behavior:

1. dgl version 1.1.1 (from pip)
2. dglke version 0.1.2 (from pip)
3. torch version 2.0.1
4. CUDA version 11.4

## Expected behavior

## Environment

- DGL Version (e.g., 1.0):
- Backend Library & Version (e.g., PyTorch 0.4.1, MXNet/Gluon 1.3):
- OS (e.g., Linux):
- How you installed DGL (`conda`, `pip`, source):
- Build command you used (if compiling from source):
- Python version:
- CUDA/cuDNN version (if applicable):
- GPU models and configuration (e.g. V100):
- Any other relevant information:

## Additional context

Tried to run the test code in the documentation here: https://aws-dglke.readthedocs.io/en/latest/install.html (Have a quick test part). It errors out with this message "ModuleNotFoundError: No module named 'dgl.contrib'"