Bump chai from 3.5.0 to 4.3.7

Bumps [chai](https://github.com/chaijs/chai) from 3.5.0 to 4.3.7.
- [Release notes](https://github.com/chaijs/chai/releases)
- [Changelog](https://github.com/chaijs/chai/blob/4.x.x/History.md)
- [Commits](chaijs/chai@3.5.0...v4.3.7)

---
updated-dependencies:
- dependency-name: chai
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -32,7 +32,7 @@
     "babel-loader": "^8.0.6",
     "body-parser": "^1.15.2",
     "browserify": "^17",
-    "chai": "^3.5.0",
+    "chai": "^4.3.7",
     "chai-as-promised": "^6.0.0",
     "cls-bluebird": "^2.0.1",
     "compression": "^1.6.2",