chore(package): update eslint to version 6.6.0

Closes #27

Author: greenkeeper[bot]

package.json

@@ -26,7 +26,7 @@
   },
   "devDependencies": {
     "ava": "2.2.0",
-    "eslint": "6.1.0",
+    "eslint": "6.6.0",
     "eslint-config-es2015": "1.1.0",
     "eslint-config-prettier": "6.0.0",
     "esm": "3.2.25",