webcolors version problem

[nictru]

When installing cellbender via conda, I encountered an error during report creation, where the webcolors package tried to use the walrus operator, which is not available in Python 3.7 yet. webcolors is an indirect dependency via jupyter (nbconvert) as far as I've seen.

Was able to fix it by sticking webcolors to 1.13. Versions larger than 1.13 require Python 3.8 or later.