chore(deps-dev): bump cz-conventional-changelog from 2.1.0 to 3.1.0

Bumps [cz-conventional-changelog](https://github.com/commitizen/cz-conventional-changelog) from 2.1.0 to 3.1.0.
- [Release notes](https://github.com/commitizen/cz-conventional-changelog/releases)
- [Commits](commitizen/cz-conventional-changelog@v2.1.0...v3.1.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -28,7 +28,7 @@
   "devDependencies": {
     "vows": ">=0.8.1",
     "chai": "^4.1.2",
-    "cz-conventional-changelog": "^2.0.0",
+    "cz-conventional-changelog": "^3.1.0",
     "jsdoc-to-markdown": "^3.0.0",
     "markdown-doctest": "^0.9.1",
     "mocha": "^4.0.0",