chore: vuepress-theme-vue should be a dev dep

Author: yyx990803

package.json

@@ -88,7 +88,6 @@
     "vue-server-renderer": "^2.5.16",
     "vue-template-compiler": "^2.5.16",
     "vuepress-html-webpack-plugin": "^3.2.0",
-    "vuepress-theme-vue": "^1.0.0",
     "webpack": "^4.5.0",
     "webpack-chain": "^4.6.0",
     "webpack-merge": "^4.1.2",
@@ -101,6 +100,7 @@
     "eslint": "^4.19.1",
     "eslint-plugin-vue-libs": "^2.1.0",
     "lint-staged": "^7.0.4",
+    "vuepress-theme-vue": "^1.0.0",
     "yorkie": "^1.0.3"
   },
   "engines": {