Merge pull request #277 from textpattern/greenkeeper/stylelint-13.1.0

Update stylelint to the latest version 🚀

Author: philwareham

package.json

@@ -26,7 +26,7 @@
     "grunt-stylelint": "0.13.0",
     "load-grunt-tasks": "5.1.0",
     "sass": "1.24.4",
-    "stylelint": "12.0.1",
+    "stylelint": "13.1.0",
     "stylelint-order": "4.0.0",
     "stylelint-scss": "3.14.2"
   },