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

Closes #33

Author: greenkeeper[bot]

package.json

@@ -30,7 +30,7 @@
     "@semantic-release/github": "^4.2.7",
     "@semantic-release/npm": "^3.2.2",
     "commitizen": "^2.9.6",
-    "cz-conventional-changelog": "^2.1.0",
+    "cz-conventional-changelog": "^3.1.0",
     "husky": "^0.14.3",
     "semantic-release": "^15.0.2",
     "vue-cli": "^2.9.3"