Pin dependency versions for 1.0-1

[edwardjkim]

Description of changes:

Pins versions for all major dependencies. We have had too many issues related to Conda/Python/libraries getting upgraded inadvertently when a CodeBuild build is triggered. This PR pins the versions in requirements.txt to a specific version or puts an upper bound.

The versions were inspected with pip freeze:

docker run 246618743249.dkr.ecr.us-west-2.amazonaws.com/sagemaker-xgboost:1.0-1-cpu-py3 sh -c 'python -m pip freeze'

See also #140.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[edmrossi]

🚢