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

Closes #94

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "codecov": "3.5.0",
     "commitizen": "^3.1.1",
     "concurrently": "^4.0.1",
-    "cz-conventional-changelog": "^2.1.0",
+    "cz-conventional-changelog": "^3.1.0",
     "eslint": "^5.16.0",
     "express": "^4.16.4",
     "istanbul": "^0.4.5",