fix(package): update react-dom to version 15.6.1

Author: greenkeeper[bot]

package.json

@@ -12,7 +12,7 @@
   "dependencies": {
     "classnames": "^2.2.5",
     "react": "15.5.4",
-    "react-dom": "15.5.4"
+    "react-dom": "15.6.1"
   },
   "devDependencies": {
     "babel-cli": "^6.24.1",