Update chai requirement from ~1.8.1 to ~4.2.0

Updates the requirements on [chai](https://github.com/chaijs/chai) to permit the latest version.
- [Release notes](https://github.com/chaijs/chai/releases)
- [Changelog](https://github.com/chaijs/chai/blob/master/History.md)
- [Commits](https://github.com/chaijs/chai/commits/4.2.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

package.json

@@ -11,7 +11,7 @@
   "devDependencies": {
     "mocha": "~1.17.0",
     "csv": "~0.3.6",
-    "chai": "~1.8.1"
+    "chai": "~4.2.0"
   },
   "scripts": {
     "test": "mocha tests/"