Add d3-color to jest.config.js

Author: PeWu

jest.config.js

@@ -6,6 +6,7 @@ module.exports = {
   },
   moduleNameMapper: {
     "d3-array": "<rootDir>/node_modules/d3-array/dist/d3-array.js",
+    "d3-color": "<rootDir>/node_modules/d3-color/dist/d3-color.js",
     "d3-hierarchy": "<rootDir>/node_modules/d3-hierarchy/dist/d3-hierarchy.js",
     "d3-selection": "<rootDir>/node_modules/d3-selection/dist/d3-selection.js",
     "d3-transition": "<rootDir>/node_modules/d3-transition/dist/d3-transition.js",