chore(package): update eslint to version 6.6.0

Closes #55

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
   },
   "devDependencies": {
     "chai": "^4.1.2",
-    "eslint": "^4.11.0",
+    "eslint": "^6.6.0",
     "eslint-config-pedant": "^1.0.0",
     "mocha": "^5.0.0",
     "nyc": "^11.3.0",