Update envirnment.yml to get the latest ray version

[magedhelmy1]

Hi,

Can you kindly update the environment.yml to reflect the latest ray version?

Currently, it installs ray at '0.8.7' when using conda env create -f environment.yml while ray is at release 1.2

[grechaw]

I'm giving this a shot as a I work my way through this tutorial. If it works all right I'll include it in a PR.

[ceteri]

Thank you @magedhelmy1 @grechaw -

Does that work better now?

There may still be a flurry of deprecation warnings from holoviews
FWIW, we're rewriting the 01-Ray-Tasks.ipynb notebook to simplify it and remove a few problematic dependencies.