Update the Iris color picker to version 1.0.6.

Changes: https://github.com/Automattic/Iris/compare/1.0.4...1.0.6

props mattwiebe.
fixes #30365.

git-svn-id: https://develop.svn.wordpress.org/trunk@30551 602fd350-edb4-49c9-b593-d223f7449a82