chore(package): update commitizen to version 4.0.1

Closes #22

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "babel-cli": "6.26.0",
     "babel-preset-es2015": "6.24.1",
     "babel-preset-react": "6.24.1",
-    "commitizen": "2.9.6",
+    "commitizen": "4.0.1",
     "conventional-changelog-cli": "1.3.21",
     "cz-conventional-changelog": "2.1.0",
     "esdoc": "1.0.4",