Bump glob-parent, flarum-webpack-config and webpack in /js (#34)

Removes [glob-parent](https://github.com/gulpjs/glob-parent). It's no longer used after updating ancestor dependencies [glob-parent](https://github.com/gulpjs/glob-parent), flarum-webpack-config and [webpack](https://github.com/webpack/webpack). These dependencies need to be updated together.


Removes `glob-parent`

Updates `flarum-webpack-config` from 1.0.0 to 2.0.2

Updates `webpack` from 4.46.0 to 5.90.1
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v4.46.0...v5.90.1)

---
updated-dependencies:
- dependency-name: glob-parent
  dependency-type: indirect
- dependency-name: flarum-webpack-config
  dependency-type: direct:production
- dependency-name: webpack
  dependency-type: direct:production
...

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