Bump chai from 3.5.0 to 4.3.4 in /reviewable

Bumps [chai](https://github.com/chaijs/chai) from 3.5.0 to 4.3.4.
- [Release notes](https://github.com/chaijs/chai/releases)
- [Changelog](https://github.com/chaijs/chai/blob/main/History.md)
- [Commits](chaijs/chai@3.5.0...v4.3.4)

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

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

Author: dependabot[bot]

reviewable/package.json

@@ -23,7 +23,7 @@
   "homepage": "https://github.com/bayesimpact/bayes-developer-setup#readme",
   "funding": "https://www.helloasso.com/associations/bayes-impact-france/formulaires/5",
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.3.4",
     "eslint": "^6.x.x",
     "lodash": "4.x.x",
     "mocha": "^2.5.3"