chore(package): update eslint to version 6.7.1

Closes #22

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
   },
   "devDependencies": {
     "chai": "^3.4.0",
-    "eslint": "^3.17.1",
+    "eslint": "^6.7.1",
     "mocha": "^3.2.0"
   },
   "scripts": {