chore(package): update commitizen to version 4.0.0

Closes #11

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "@types/node": "11.9.3",
     "chai": "4.2.0",
     "chai-as-promised": "7.1.1",
-    "commitizen": "3.0.5",
+    "commitizen": "4.0.0",
     "conventional-changelog-cli": "2.0.11",
     "cz-conventional-changelog": "2.1.0",
     "husky": "1.3.1",