fix: install package requirements

[arthurdjn]

Cannot import the python API after installing from pip:

pip install git+https://github.com/JIA-Lab-research/SparseTransformer

CUDA / C++ extension installed correctly:

python -c "import sptr_cuda; print('extension ok')"
  extension ok

But importing the pyhon API raises:

python -c "import sptr"
  ModuleNotFoundError: No module named 'sptr'

This fix registers the sptr in the setup so that it is installed when doing the above command.
Also added timm dependency which was missing.