chore: update version of yarn used

package.json

@@ -19,5 +19,5 @@
     "vuepress": "2.0.0-rc.2",
     "vuepress-plugin-search-pro": "^2.0.0-rc.16"
   },
-  "packageManager": "yarn@4.0.2"
+  "packageManager": "yarn@4.1.1"
 }