chore(package): update commitizen to version 4.0.0

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "ava": "^2.0.0",
     "clear-module": "^4.0.0",
     "codecov": "^3.0.0",
-    "commitizen": "^3.0.0",
+    "commitizen": "^4.0.0",
     "cz-conventional-changelog": "^2.0.0",
     "delay": "^4.0.0",
     "dockerode": "^2.5.3",