Bump mini-css-extract-plugin from 2.7.6 to 2.9.0

Bumps [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) from 2.7.6 to 2.9.0.
- [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@v2.7.6...v2.9.0)

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

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

package.json

@@ -66,7 +66,7 @@
     "ignore": "^5.2.4",
     "lazysizes": "^5.3.2",
     "lodash": "^4.17.21",
-    "mini-css-extract-plugin": "^2.7.6",
+    "mini-css-extract-plugin": "^2.9.0",
     "normalise": "^10.0.0",
     "normalize.css": "^8.0.1",
     "null-loader": "^4.0.1",