chore(package): update semantic-release to version 15.1.7

Closes #14

Author: greenkeeper[bot]

package.json

@@ -112,7 +112,7 @@
     "rollup-plugin-node-resolve": "^3.0.0",
     "rollup-plugin-sourcemaps": "^0.4.2",
     "rollup-plugin-typescript2": "^0.10.0",
-    "semantic-release": "^12.2.4",
+    "semantic-release": "^15.1.7",
     "travis-deploy-once": "^4.3.3",
     "ts-jest": "^22.0.0",
     "ts-node": "^4.1.0",