chore: upgrade eslint from 6.1.0 to 6.3.0

Snyk has created this PR to upgrade eslint from 6.1.0 to 6.3.0.

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

See this project in Snyk:
https://app.snyk.io/org/richm-ww/project/816bc827-3052-4910-9cec-85d6bd42cb31?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -27,7 +27,7 @@
     "babel-eslint": "10.0.2",
     "babel-preset-env": "^1.7.0",
     "babel-preset-stage-0": "6.24.1",
-    "eslint": "6.1.0",
+    "eslint": "6.3.0",
     "eslint-config-airbnb-base": "13.2.0",
     "eslint-plugin-import": "2.18.2",
     "node-mocks-http": "1.7.6",