fix: style

Author: xiaoxiaojx

src/content/plugins/virtual-url-plugin.mdx

@@ -30,7 +30,7 @@ console.log(msg);
 Create a virtual module that generates build information
 
 ```javascript
-const webpack = require("webpack")
+const webpack = require('webpack')
 
 new webpack.experiments.schemes.VirtualUrlPlugin({
   buildInfo: {