fix: upgrade eslint from 5.0.0 to 5.16.0

Snyk has created this PR to upgrade eslint from 5.0.0 to 5.16.0.

See this package in NPM:
https://www.npmjs.com/package/eslint

See this project in Snyk:
https://app.snyk.io/org/davidkindler/project/6865432e-9ae7-40aa-ab6d-807d59d4dccc?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -17,7 +17,7 @@
     "css-loader": "1.0.0",
     "dotenv": "4.0.0",
     "enzyme-to-json": "^3.3.1",
-    "eslint": "5.0.0",
+    "eslint": "5.16.0",
     "eslint-config-react-app": "^2.0.0",
     "eslint-loader": "1.9.0",
     "eslint-plugin-flowtype": "2.50.3",