Update clean-webpack-plugin requirement from ^2.0.2 to ^3.0.0

Updates the requirements on [clean-webpack-plugin](https://github.com/johnagan/clean-webpack-plugin) to permit the latest version.
- [Release notes](https://github.com/johnagan/clean-webpack-plugin/releases)
- [Commits](johnagan/clean-webpack-plugin@v2.0.2...v3.0.0)

packages/plugin-documentation/package.json

@@ -64,7 +64,7 @@
     "@types/webpack": "^4.4.32",
     "babel-loader": "^8.0.6",
     "bili": "^4.8.0",
-    "clean-webpack-plugin": "^2.0.2",
+    "clean-webpack-plugin": "^3.0.0",
     "css-loader": "^2.1.1",
     "glob-all": "^3.1.0",
     "mini-css-extract-plugin": "^0.7.0",