fix: upgrade chai from 4.2.0 to 4.3.4

Snyk has created this PR to upgrade chai from 4.2.0 to 4.3.4.

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

See this project in Snyk:
https://app.snyk.io/org/postman/project/7a451467-46a9-400f-95e9-f31415bd6fff?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -26,7 +26,7 @@
   "dependencies": {},
   "devDependencies": {
     "browserify": "16.5.1",
-    "chai": "4.2.0",
+    "chai": "4.3.4",
     "chalk": "2.4.2",
     "colors": "1.4.0",
     "karma": "3.1.4",