chore(package): update semantic-release to version 12.4.1

Closes #24

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
     "loopback-testing": "1.4.0",
     "mocha": "3.4.2",
     "nyc": "11.0.3",
-    "semantic-release": "6.3.6",
+    "semantic-release": "12.4.1",
     "validate-commit-msg": "2.12.3"
   },
   "config": {