Merge branch 'structure_tensor_wrapper' into 'main'

docs/processing.md

qim3d/processing/__init__.py

qim3d/processing/filters.py

qim3d/processing/structure_tensor.py

qim3d/tests/processing/test_structure_tensor.py

qim3d/viz/__init__.py

qim3d/viz/img.py

qim3d/viz/structure_tensor.py

requirements.txt

setup.py