chore(package): update eslint to version 6.5.0

Closes #135

Author: greenkeeper[bot]

package.json

@@ -60,7 +60,7 @@
     "yargs": "^12.0.1"
   },
   "devDependencies": {
-    "eslint": "^5.0.0",
+    "eslint": "^6.5.0",
     "eslint-config-gulp": "^3.0.0",
     "esvalidate": "^0.1.3",
     "jsonlint-cli": "^1.0.1"