ci(deps-dev): bump optimize-css-assets-webpack-plugin

Bumps [optimize-css-assets-webpack-plugin](https://github.com/NMFR/optimize-css-assets-webpack-plugin) from 5.0.3 to 6.0.1.
- [Release notes](https://github.com/NMFR/optimize-css-assets-webpack-plugin/releases)
- [Commits](NMFR/optimize-css-assets-webpack-plugin@v5.0.3...v6.0.1)

---
updated-dependencies:
- dependency-name: optimize-css-assets-webpack-plugin
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

packages/app/package.json

@@ -205,7 +205,7 @@
     "normalize-path": "^3.0.0",
     "null-loader": "^3.0.0",
     "on-headers": "^1.0.1",
-    "optimize-css-assets-webpack-plugin": "^5.0.3",
+    "optimize-css-assets-webpack-plugin": "^6.0.1",
     "penpal": "^4.0.0",
     "plantuml-encoder": "^1.2.5",
     "postcss-loader": "^3.0.0",