Fix: Preserve hyperparameter order when invoking training jobs

[vsimkus]

Fixes #221.

Removed the alphanumeric sorting of the hyperparameters in

sagemaker-training-toolkit/src/sagemaker_training/mapping.py

Lines 65 to 78 in 628166c

	def to_cmd_args(mapping): # type: (dict) -> list
	"""Transform a dictionary in a list of cmd arguments.
	Example:
	>>>args = mapping.to_cmd_args({'model_dir': '/opt/ml/model', 'batch_size': 25})
	>>>
	>>>print(args)
	['--model_dir', '/opt/ml/model', '--batch_size', 25]
	Args:
	mapping (dict[str, object]): A Python mapping.
	Returns:
	(list): List of cmd arguments.
	"""
	sorted_keys = sorted(mapping.keys())

This makes sure that training scripts are invoked with the same order of hyperparameters as passed in the hyperparameters argument to the SageMaker Estimator class. This sorting was undocumented and as argued in issue #221 can cause issues for scripts where order of the arguments matters.

I have updated the unit tests in test_mapping.py to verify that the order of the arguments is preserved.

I ran the unit tests with tox -e py310 -- -s -vv test/unit and they passed. Let's see if the CI tests find anything...

Merge Checklist

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• I have read the CONTRIBUTING doc
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• I have updated any necessary documentation, including READMEs

Tests

• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have checked that my tests are not configured for a specific region or account (if appropriate)

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[prtsh]

Approved. Change replaces the args sorting so that the order of the hyper-param cli args is preserved. Do not see any intended harm with this change as the cli args are order agnostic.