chore(deps-dev): bump mini-css-extract-plugin

Bumps [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) from 2.4.5 to 2.9.1.
- [Release notes](https://github.com/webpack-contrib/mini-css-extract-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/mini-css-extract-plugin/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/mini-css-extract-plugin@v2.4.5...v2.9.1)

---
updated-dependencies:
- dependency-name: mini-css-extract-plugin
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

generators/client/templates/react/package.json

@@ -60,7 +60,7 @@
     "jest-sonar-reporter": "2.0.0",
     "json-loader": "0.5.7",
     "merge-jsons-webpack-plugin": "2.0.1",
-    "mini-css-extract-plugin": "2.4.5",
+    "mini-css-extract-plugin": "2.9.1",
     "postcss-loader": "6.2.1",
     "postcss-rtlcss": "3.5.0",
     "react-infinite-scroll-component": "6.1.0",