chore(package): update semantic-release to version 15.13.31

Closes #6

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
     "loopback-testing": "^1.4.0",
     "mocha": "latest",
     "nyc": "latest",
-    "semantic-release": "^6.3.2"
+    "semantic-release": "^15.13.31"
   },
   "config": {
     "commitTypeMap": {