ci: switch to dev branch for Vue core

Author: yyx990803

package.json

@@ -54,7 +54,7 @@
     "phantomjs": "^1.9.18",
     "selenium-server": "2.47.1",
     "style-loader": "^0.12.3",
-    "vue": "yyx990803/vue#1.0.0-beta",
+    "vue": "yyx990803/vue#dev",
     "vue-loader": "^3.0.3",
     "webpack": "^1.11.0",
     "webpack-dev-server": "^1.10.1"