chore(package): update semantic-release to version 15.0.0

Closes #10

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "lint-staged": "^4.2.1",
     "mocha": "^4.0.0",
     "prettier-standard": "^6.0.0",
-    "semantic-release": "^7.0.1",
+    "semantic-release": "^15.0.0",
     "standard": "^11.0.0"
   },
   "lint-staged": {