chore(package): update semantic-release to version 15.1.5

Closes #14

Author: greenkeeper[bot]

package.json

@@ -66,7 +66,7 @@
     "jest": "^22.0.6",
     "nodemon": "^1.14.11",
     "prettier": "^1.10.2",
-    "semantic-release": "^12.4.1"
+    "semantic-release": "^15.1.5"
   },
   "jest": {
     "coverageReporters": [