Bump psutil and sagemaker-containers version

[rizwangilani]

Bump psutil from 5.4.8 to 5.6.7 and sagemaker-containers from 2.5.6 to 2.8.3

Issue #, if available:

Description of changes:

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[edwardjkim]

• Did we run integration tests?
• Does sagemaker-containers 2.8.3 have the fix for the requirements.txt issue? Is there a way for us to test this?
• Does XGBoost have network isolation?

[aws-patlin]

@edwardjkim Just an FYI, the issues with requirements.txt and network isolation should not affect XGBoost. Those bugs were present in the code path of modules.download_and_install and entrypoint.run, while in XGBoost we call modules.run_module.

[edwardjkim]

Thanks @aws-patlin, that makes sense. Can we just make sure to manually run integration tests as a sanity check before merging since this involves sagemaker-containers?