chore(package): update cz-conventional-changelog to version 3.1.0

Closes #20

Author: greenkeeper[bot]

package.json

@@ -91,7 +91,7 @@
     "commitizen": "^2.9.6",
     "coveralls": "^3.0.0",
     "cross-env": "^5.0.1",
-    "cz-conventional-changelog": "^2.0.0",
+    "cz-conventional-changelog": "^3.1.0",
     "husky": "^0.14.0",
     "jest": "^23.2.0",
     "lint-staged": "^7.0.0",