Constrain scikit-image

[marcelotrevisani]

Checklist

• Used a fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[marcelotrevisani]

That is necessary because of the latest scikit-image removed one function which caffe is using
https://github.com/scikit-image/scikit-image/blob/master/doc/release/release_0.16.rst#api-changes

caffe uses as_grey function and it was renamed to as_gray

I think we should not patch it to fix this problem because we might face new problems. I will just constrain the scikit-image and it will be enough for now

[marcelotrevisani]

@conda-forge-admin, please rerender

[marcelotrevisani]

@ocefpaf , It would be nice to mark the packages with build number 203 and 204 as broken as well.