text: Title: Drop `scipy` from dev dependencies
  Body: ## 🚀 Feature
  The scipy package is just used in one place. So, we can figure out how to test the case without it
  
  ```
  $ git grep 'scipy'
  docker/Dockerfile:     /opt/conda/bin/conda install -y python=$PYTHON_VERSION numpy pyyaml scipy ipython mkl mkl-include cython typing && \
  requirements/requirements-dev.txt:scipy
  test/losses/test_hd.py:from scipy.ndimage import convolved
  ```
  
   https://github.com/kornia/kornia/blob/216aa9d2f10f9300bffe952b1583f03b7f833be5/test/losses/test_hd.py#L49
  
  
  ## Motivation
  reduce the number of dependencies at kornia 