chore(package): update semantic-release to version 15.0.1

Closes #24

Author: greenkeeper[bot]

package.json

@@ -66,7 +66,7 @@
     "loopback-testing": "^1.4.0",
     "mocha": "latest",
     "nyc": "latest",
-    "semantic-release": "^6.3.6",
+    "semantic-release": "^15.0.1",
     "sinon": "latest",
     "sinon-chai": "latest",
     "validate-commit-msg": "^2.12.2"