fixing: numpy version issue

[Stvchm9703]

added for motionGPT

• demo.py
  • for replacing the motionGPT/demo.py
  • added the default device for pytorch, as the fallback(device = torch.device("cpu"))

modified for numpy

Although I use python=3.10, but the numpy still cannot downgrade as <=1.15.
Hence I use the numpy>=1.26, <2 as baseline, to fix the mismatching issue

• tools/npy2bvh/common/quaternion.py
  • use native python float type, (see also : https://numpy.org/devdocs/release/1.20.0-notes.html)
• tools/npy2bvh/visualization/Animation.py
  • change numpy.core.umath_tests.matrix_multiply to numpy.matmul