fix: fix loading user custom script

[SuperBo]

Issue #86: I think the issue is very well mentioned here https://github.com/aws/sagemaker-inference-toolkit/issues/86 Description of changes:

Change PYTHONPATH environment after loading your python program won't affect the import paths that python will use to import libraries and modules. In order to change the import paths, we need to change "sys.path" variable.

Testing done:

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[Otje89]

What is the status of this merge request? I'm experiencing the same issue and found that it was indeed caused by the same line of code. It would be great to have this updated.

[Alex-Wenner-FHR]

I am still experiencing this issue in 2024. Has there been any fix? This looks like a simple solution given this is indeed the issue.

[ViktorMalesevic]

Same issue here. When adding sagemaker-inference to my own container, this line: https://github.com/aws/sagemaker-inference-toolkit/blob/f79853d4e307a983ec5d76980be5ed6a9feb8c0e/src/sagemaker_inference/default_handler_service.py#L52 forces all modules that an entrypoint will use to be copied to "/opt/ml/model/code/" and the entrypoint to be placed at the root of "/opt/ml/model/code/". This is not documented in https://github.com/aws/sagemaker-inference-toolkit/tree/master?tab=readme-ov-file#implementation-steps