fix: upgrade chai from 4.2.0 to 4.3.6

Snyk has created this PR to upgrade chai from 4.2.0 to 4.3.6.

See this package in npm:
https://www.npmjs.com/package/chai

See this project in Snyk:
https://app.snyk.io/org/postman/project/8519ba8e-6a7d-469a-88b3-7891b4c1c14e?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -32,7 +32,7 @@
   },
   "devDependencies": {
     "browserify": "14.5.0",
-    "chai": "4.2.0",
+    "chai": "4.3.6",
     "chalk": "2.4.2",
     "eslint": "5.16.0",
     "dependency-check": "2.10.1",