Bump chai from 3.5.0 to 4.1.2

Bumps [chai](https://github.com/chaijs/chai) from 3.5.0 to 4.1.2.
- [Release notes](https://github.com/chaijs/chai/releases)
- [Changelog](https://github.com/chaijs/chai/blob/master/History.md)
- [Commits](chaijs/chai@3.5.0...4.1.2)

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

package.json

@@ -28,7 +28,7 @@
   "devDependencies": {
     "broccoli": "^0.16.9",
     "broccoli-asset-rev": "^2.4.5",
-    "chai": "^3.5.0",
+    "chai": "^4.1.2",
     "ember-cli": "~3.0.1",
     "ember-cli-content-security-policy": "^0.4.0",
     "ember-cli-dependency-checker": "^2.0.0",