Bump @fortawesome/free-brands-svg-icons from 5.6.0 to 5.6.3 in /frontend

Bumps [@fortawesome/free-brands-svg-icons](https://github.com/FortAwesome/Font-Awesome) from 5.6.0 to 5.6.3.
- [Release notes](https://github.com/FortAwesome/Font-Awesome/releases)
- [Changelog](https://github.com/FortAwesome/Font-Awesome/blob/master/CHANGELOG.md)
- [Commits](FortAwesome/Font-Awesome@5.6.0...5.6.3)

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