[Security] Bump omniauth from 1.9.1 to 2.0.4
[Security] Bump omniauth from 1.9.1 to 2.0.4

Bumps [omniauth](https://github.com/omniauth/omniauth) from 1.9.1 to 2.0.4. **This update includes a security fix.**
- [Release notes](https://github.com/omniauth/omniauth/releases)
- [Commits](https://github.com/omniauth/omniauth/compare/v1.9.1...v2.0.4)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
rubymonsters/speakerinnen_liste,rubymonsters/speakerinnen_liste,rubymonsters/speakerinnen_liste