Update dependency eslint to v5 (#13)

Author: renovate[bot]

package.json

@@ -13,7 +13,7 @@
   },
   "dependencies": {
     "babel-eslint": "8.2.3",
-    "eslint": "4.19.1",
+    "eslint": "5.7.0",
     "eslint-plugin-prettier": "2.6.0",
     "prettier": "1.14.3"
   }