fix(package): update eslint to version 6.4.0

Closes #4

Author: greenkeeper[bot]

package.json

@@ -26,7 +26,7 @@
   },
   "dependencies": {
     "babel-eslint": "^7.1.1",
-    "eslint": "^3.17.1",
+    "eslint": "^6.4.0",
     "eslint-config-airbnb": "^14.1.0",
     "eslint-plugin-import": "^2.2.0"
   }