Rely on dask-core version constraints

[jakirkham]

Builds on PR ( conda-forge/dask-core-feedstock#171 ) to rely on dask-core to have the right version constraints applied to these. That way the dependencies can just be listed here (without needing to worry about versions)

---

Checklist

• Used a personal 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-webservices]

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.

[jakirkham]

If done, this would be best rolled into a Dask & Distributed release

[jakirkham]

cc @jrbourbeau ( as this builds on PR conda-forge/dask-core-feedstock#171 )

[jakirkham]

Should add this is ready whenever PR ( conda-forge/dask-core-feedstock#171 ) is incorporated in dask-core. It is only marked as draft to ensure that this happens afterward