chore(package): update eslint-config-airbnb to version 18.1.0

Closes #25

Author: greenkeeper[bot]

package.json

@@ -53,7 +53,7 @@
     "chai": "^4.1.2",
     "cross-env": "^5.2.0",
     "eslint": "^5.3.0",
-    "eslint-config-airbnb": "^17.0.0",
+    "eslint-config-airbnb": "^18.1.0",
     "eslint-plugin-import": "^2.13.0",
     "eslint-plugin-jsx-a11y": "^6.1.1",
     "eslint-plugin-react": "^7.10.0",