Update semantic-release to the latest version 🚀 (#22)

* chore(package): update semantic-release to version 15.9.15

* chore(package): update lockfile

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
     "codecov": "3.1.0",
     "jest": "23.4.1",
     "nodemon": "1.18.4",
-    "semantic-release": "15.9.14",
+    "semantic-release": "15.9.15",
     "smee-client": "1.0.2",
     "standard": "12.0.0"
   },