chore(package): update stylelint to version 9.0.0

Author: greenkeeper[bot]

package.json

@@ -71,7 +71,7 @@
     "react-dom": "^16.0.0",
     "react-test-renderer": "^16.0.0",
     "rimraf": "^2.6.2",
-    "stylelint": "^8.0.0",
+    "stylelint": "^9.0.0",
     "stylelint-config-standard": "^17.0.0"
   },
   "engines": {