chore(package): update @commitlint/config-conventional to version 8.0.0

Closes #283

Author: greenkeeper[bot]

package.json

@@ -52,7 +52,7 @@
   },
   "devDependencies": {
     "@commitlint/cli": "^6.0.2",
-    "@commitlint/config-conventional": "^6.0.2",
+    "@commitlint/config-conventional": "^8.0.0",
     "@commitlint/prompt": "^6.0.2",
     "chai": "^4.1.2",
     "commitizen": "^2.9.6",