SM_CHANNEL_TRAIN error when building workflow

**Link to the notebook**
[here is the link to the notebook](https://sagemaker-examples.readthedocs.io/en/latest/step-functions-data-science-sdk/machine_learning_workflow_abalone/machine_learning_workflow_abalone.html)

**Describe the bug**
Error when executing the state machine in the stepfunctions

**To reproduce**
Just follow exact steps in the above notebook
**Logs**
If applicable, add logs to help explain your problem.

Here is the log

"FailureReason": "AlgorithmError: framework error: \nTraceback (most recent call last):\n File \"/miniconda3/lib/python3.7/site-packages/sagemaker_containers/_trainer.py\", line 84, in train\n entrypoint()\n File \"/miniconda3/lib/python3.7/site-packages/sagemaker_xgboost_container/training.py\", line 94, in main\n train(framework.training_env())\n File \"/miniconda3/lib/python3.7/site-packages/sagemaker_xgboost_container/training.py\", line 90, in train\n run_algorithm_mode()\n File \"/miniconda3/lib/python3.7/site-packages/sagemaker_xgboost_container/training.py\", line 56, in run_algorithm_mode\n train_path = os.environ[sm_env_constants.SM_CHANNEL_TRAIN]\n File \"/miniconda3/lib/python3.7/os.py\", line 681, in __getitem__\n raise KeyError(key) from None\nKeyError: 'SM_CHANNEL_TRAIN'\n\n'SM_CHANNEL_TRAIN', exit code: 1",