chore(deps): rollback dependency mini-css-extract-plugin to v2.4.5

kktjs/kkt#340
TypeError: MiniCssExtractPlugin is not a constructor

Author: jaywcjlove

package.json

@@ -62,7 +62,7 @@
     "husky": "7.0.4",
     "kkt": "7.0.5",
     "lint-staged": "12.1.7",
-    "mini-css-extract-plugin": "2.5.0",
+    "mini-css-extract-plugin": "2.4.5",
     "prettier": "2.5.1",
     "react": "17.0.2",
     "react-dom": "17.0.2",