chore: upgrade vuepress to v1-alpha.23

Author: PeachScript

package.json

@@ -80,7 +80,7 @@
     "vue": "^2.5.17",
     "vue-loader": "^15.4.1",
     "vue-template-compiler": "^2.5.17",
-    "vuepress": "^1.0.0-alpha.9",
+    "vuepress": "^1.0.0-alpha.23",
     "webpack": "^4.17.2",
     "webpack-cli": "^3.1.0",
     "webpack-dev-server": "^3.1.8"