Update mini-css-extract-plugin requirement from ^0.5.0 to ^0.6.0
Update mini-css-extract-plugin requirement from ^0.5.0 to ^0.6.0

Updates the requirements on [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) to permit the latest version.
- [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](https://github.com/webpack-contrib/mini-css-extract-plugin/compare/v0.5.0...v0.6.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
nextcloud/deck,nextcloud/deck,juliushaertl/deck,juliushaertl/deck,juliushaertl/deck,nextcloud/deck