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

Closes #12

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "codecov": "^3.1.0",
     "commitizen": "^3.0.5",
     "coveralls": "^3.0.2",
-    "cz-conventional-changelog": "^2.1.0",
+    "cz-conventional-changelog": "^3.1.0",
     "eslint": "^5.9.0",
     "eslint-config-standard": "^12.0.0",
     "eslint-plugin-import": "^2.14.0",