removes artifacts from no longer used heroku deployment

Author: itsthatguy

.buildpacks

@@ -11,7 +11,6 @@
     "dev": "concurrently --kill-others --prefix=name --names=server,eslint --prefix-colors=green,magenta \"npm run dev:server\" \"npm run dev:lint\"",
     "dev:server": "babel-watch --watch src test/server.js",
     "dev:lint": "esw src/ --changed --watch",
-    "heroku-postbuild": "npm run build",
     "prepublishOnly": "npm run build"
   },
   "author": "",