chore: add missing dependency for semantic release

Author: Johannes J. Schmidt

package.json

@@ -33,7 +33,8 @@
   "devDependencies": {
     "semantic-release": "^12.4.1",
     "standard": "^11.0.0",
-    "tap": "^11.1.1"
+    "tap": "^11.1.1",
+    "travis-deploy-once": "^4.3.4"
   },
   "standard": {
     "ignore": [