chore(package): update eslint to version 5.12.1

Closes #48

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
     "@carsy/eslint-config": "^0.4.0",
     "ava": "^0.25.0",
     "coveralls": "^3.0.0",
-    "eslint": "^4.19.1",
+    "eslint": "^5.12.1",
     "nyc": "^11.7.1",
     "tap-nyan": "1.1.0"
   },