Object to world transformation incorrect

In our tests, we noticed that the ground truth object to world transformation is incorrect. If we fix the following line to use @ to perform actual matrix multiplication instead of elementwise multiplication, it will give the correct result.

https://github.com/Simple-Robotics/cosypose/blob/1e45363d0ac061d0cc2c0f42eb4c745bbf2b951e/cosypose/datasets/bop.py#L132

Fixed in PR #20 