calendar: upgrade color-slicer

fixes CNVS-12227

test plan:
  * create at least 20 courses
  * enable and open calendar 2
  * verify that all neighboring courses have visually
      distinctive colors

Change-Id: I2d3f9fb0e669cbc4fcda55a432cba07c18dbdfb5
Reviewed-on: https://gerrit.instructure.com/32931
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Joel Hough <joel@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Braden Anderson <banderson@instructure.com>