add heroku postbuild

Author: cxspxr

package.json

@@ -6,16 +6,17 @@
     "serve": "vue-cli-service serve",
     "build": "vue-cli-service build",
     "lint": "vue-cli-service lint",
-    "test:unit": "vue-cli-service test:unit"
+    "test:unit": "vue-cli-service test:unit",
+    "heroku-postbuild": "npm run build"
   },
   "dependencies": {
     "express": "^4.16.3",
-    "vue": "^2.5.17"
+    "vue": "^2.5.17",
+    "@vue/cli-service": "^3.0.4" 
   },
   "devDependencies": {
     "@vue/cli-plugin-babel": "^3.0.4",
     "@vue/cli-plugin-unit-mocha": "^3.0.4",
-    "@vue/cli-service": "^3.0.4",
     "@vue/test-utils": "^1.0.0-beta.20",
     "axios": "^0.18.0",
     "chai": "^4.1.2",