Python package should only depend on `opencv-python-contrib`

[Breakthrough]

Right now the Python package depends on both opencv-python and opencv-python-contrib. This is incorrect, and it should only depend on the latter [1]:

There are four different packages (see options 1, 2, 3 and 4 below) and you should SELECT ONLY ONE OF THEM. Do not install multiple different packages in the same environment. There is no plugin architecture: all the packages use the same namespace (cv2). If you installed multiple different packages in the same environment, uninstall them all with pip uninstall and reinstall only one package.

[1] https://pypi.org/project/opencv-python/