chore(package): update eslint to version 6.5.1

Closes #25

Author: greenkeeper[bot]

package.json

@@ -34,7 +34,7 @@
     "chai": "^4.0.2",
     "codecov": "^3.0.0",
     "docdash": "^0.4.0",
-    "eslint": "^5.0.0",
+    "eslint": "^6.5.1",
     "istanbul": "^0.4.5",
     "jsdoc": "^3.4.3",
     "mocha": "^5.0.0",