fix: windows path for experiments.css

Author: jeromehan

lib/loaders/pitcher.js

@@ -150,9 +150,14 @@ module.exports.pitch = function (remainingRequest) {
           return typeof loader === 'string' ? loader : loader.request
         })
         .join('!')
-      return `@import "${this.resourcePath}${
-        query.lang ? `.${query.lang}` : ''
-      }${this.resourceQuery}!=!-!${loaderString}!${this.resourcePath + this.resourceQuery}";`
+
+        const styleRequest = loaderUtils.stringifyRequest(
+          this,
+          `${this.resourcePath}${query.lang ? `.${query.lang}` : ''}${
+            this.resourceQuery
+          }!=!-!${loaderString}!${this.resourcePath + this.resourceQuery}`
+        )
+        return `@import ${styleRequest};`
     }
 
     const cssLoaderIndex = loaders.findIndex(isCSSLoader)