[bug fix] Patch concat transform.

[xwjiang2010]

Fixes #331

Changes proposed in this pull request:

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[xwjiang2010]

@youliangtan I notice that there is not a lot of test coverage in the repo.
What would be a flow that you suggest that I run manual testing with?

[youliangtan]

@xwjiang2010 This concat transform patch is helpful, have this been tested e2e?

[maximilianofir]

I also experience this bug when converting actions from quaternions in the dataset to 6D representation for training.
The error occurs after the conversion, when concatenating the now larger orientation format to the action tensor.
Plus 1 request, to merge the above.