chore(deps-dev): bump webpack, file-loader and mini-css-extract-plugin

Bumps [webpack](https://github.com/webpack/webpack), [file-loader](https://github.com/webpack-contrib/file-loader) and [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin). These dependencies needed to be updated together.

Updates `webpack` from 4.43.0 to 5.94.0
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v4.43.0...v5.94.0)

Updates `file-loader` from 4.3.0 to 6.2.0
- [Release notes](https://github.com/webpack-contrib/file-loader/releases)
- [Changelog](https://github.com/webpack-contrib/file-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/file-loader@v4.3.0...v6.2.0)

Updates `mini-css-extract-plugin` from 0.8.2 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@v0.8.2...v2.9.1)

---
updated-dependencies:
- dependency-name: webpack
  dependency-type: direct:development
- dependency-name: file-loader
  dependency-type: direct:development
- dependency-name: mini-css-extract-plugin
  dependency-type: direct:development
...

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