chore(package): update eslint to version 6.7.2

Closes #17

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "babel-preset-flow": "^6.23.0",
     "chai": "4.1.2",
     "chai-http": "3.0.0",
-    "eslint": "^4.18.2",
+    "eslint": "^6.7.2",
     "eslint-config-prettier": "^2.9.0",
     "eslint-config-standard": "^11.0.0",
     "eslint-plugin-flowtype": "^2.46.1",