Describe the bug
the openslide installation steps are currently not implemented in the testing and docker building pipelines
https://github.com/Project-MONAI/MONAI/runs/2058917545?check_suite_focus=true#step:10:5509

need to follow https://github.com/openslide/openslide-python#installation