What does this PR do?

python -m mart experiment=COCO_YOLOv3_ShapeShifter trainer=gpu

This PR depends upon a lot of other PRs so I'm waiting for those PRs to be merged.

Type of change

Please check all relevant options.

[ ] Improvement (non-breaking)
[ ] Bug fix (non-breaking)
[ ] New feature (non-breaking)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update

Please describe the tests that you ran to verify your changes. Consider listing any relevant details of your test configuration.

[ ] The title is self-explanatory and the description concisely explains the PR
[ ] My PR does only one thing, instead of bundling different changes together
[ ] I list all the breaking changes introduced by this pull request
[ ] I have commented my code
[ ] I have added tests that prove my fix is effective or that my feature works
[ ] New and existing unit tests pass locally with my changes
[ ] I have run pre-commit hooks with pre-commit run -a command without errors

Make sure you had fun coding 🙃