fix(package): Update semantic-release.

Author: jakehamilton

package.json

@@ -49,7 +49,7 @@
         "jest": "^20.0.0",
         "pascal-case": "^2.0.1",
         "rimraf": "^2.6.1",
-        "semantic-release": "^15.7.1",
+        "semantic-release": "^15.8.1",
         "semver": "^5.4.0",
         "travis-deploy-once": "^5.0.1",
         "ts-jest": "^20.0.0",