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

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "parse-json": "^4.0.0",
     "rollup": "^0.56.5",
     "rollup-plugin-babel": "^3.0.3",
-    "semantic-release": "^12.4.1",
+    "semantic-release": "^15.0.0",
     "sinon": "^4.4.0",
     "sinon-stub-promise": "^4.0.0",
     "travis-deploy-once": "^4.3.4",