chore(deps): pin dependencies (#2)

Author: renovate[bot]

package.json

@@ -28,7 +28,7 @@
     "git-http-backend": "^1.0.2"
   },
   "devDependencies": {
-    "semantic-release": "^15.1.4",
-    "travis-deploy-once": "^4.4.1"
+    "semantic-release": "15.1.4",
+    "travis-deploy-once": "4.4.1"
   }
 }