chore(package): update stylelint to version 8.4.0

Closes #6

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "postcss-cli": "^2.6.0",
     "postcss-cssnext": "^2.9.0",
     "postcss-import": "^9.0.0",
-    "stylelint": "^7.7.0",
+    "stylelint": "^8.4.0",
     "stylelint-config-ticketfly": "^0.1.0"
   },
   "scripts": {