fix: upgrade expect from 23.0.0 to 23.6.0

Snyk has created this PR to upgrade expect from 23.0.0 to 23.6.0.

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

See this project in Snyk:
https://app.snyk.io/org/yowainwright/project/03b099ed-f55b-4b6c-983e-577944d94ddf?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -26,7 +26,7 @@
     "create-react-class": "^15.6.3",
     "css-loader": "^0.23.1",
     "events": "^1.0.2",
-    "expect": "^23.0.0",
+    "expect": "^23.6.0",
     "exports-loader": "^0.6.3",
     "expose-loader": "0.7.1",
     "express": "^4.14.0",