chore(package): update commitizen to version 4.0.5

Closes #31

Author: greenkeeper[bot]

package.json

@@ -38,7 +38,7 @@
     "@semantic-release/npm": "^3.0.2",
     "chai": "^4.1.2",
     "chokidar-cli": "^1.2.0",
-    "commitizen": "^2.9.6",
+    "commitizen": "^4.0.5",
     "cross-env": "^5.1.3",
     "cz-conventional-changelog": "^2.1.0",
     "es6-plato": "^1.0.16",