chore(package): update eslint to version 6.5.1

Closes #16

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "babel-preset-stage-0": "^6.24.1",
     "babel-register": "^6.26.0",
     "coveralls": "^3.0.0",
-    "eslint": "^4.5.0",
+    "eslint": "^6.5.1",
     "eslint-config-airbnb": "^17.0.0",
     "eslint-plugin-import": "^2.7.0",
     "nyc": "^11.1.0"