Listing dependencies: `openslide` and `xorg-libxcb`?

[jakirkham]

In this PR discussion ( #471 (comment) ), @bdice flagged that we have openslide and xorg-libxcb dependencies that he couldn't identify where to place in our dependencies

cucim/dependencies.yaml

Lines 256 to 258 in b738d2c

	# Not sure where these go, if anywhere:
	# - openslide
	# - xorg-libxcb

Already openslide-python is pulled in for testing

cucim/dependencies.yaml

Lines 277 to 281 in b738d2c

	- output_types: [conda]
	packages:
	- imagecodecs>=2021.6.8
	- matplotlib-base>=3.7
	- openslide-python>=1.3.0

My understanding is openslide is an optional dependency that can be built with in C++, but is not required. We don't build with it at present

Perhaps there is a better way to capture this?

[jakirkham]

@gigony do you have thoughts on how these should be handled?