fix(package): update atom-linter to version 9.0.0

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -9,7 +9,7 @@
     "atom": ">=1.0.0"
   },
   "dependencies": {
-    "atom-linter": "^8.0.0",
+    "atom-linter": "^9.0.0",
     "atom-package-deps": "^4.0.1",
     "lesshint": "^3.0.0"
   },