chore(deps): update dependency semantic-release to v15.8.0 (#22)

Author: renovate[bot]

package.json

@@ -50,7 +50,7 @@
     "rollup-plugin-node-resolve": "3.3.0",
     "rollup-plugin-replace": "2.0.0",
     "rollup-plugin-terser": "1.0.1",
-    "semantic-release": "15.7.2",
+    "semantic-release": "15.8.0",
     "tslint": "5.11.0",
     "tslint-config-prettier": "1.13.0",
     "typescript": "2.9.2"