Update dependencies and refactor code

- Bump axum from 0.7 to 0.8 and update related dependencies.
- Upgrade uuid to 1.23.1 and chrono to 0.4.44 for improved functionality.
- Update jsonwebtoken to 10.3.0, reqwest to 0.13.2, and sha2 to 0.11 for security and performance enhancements.
- Remove unused fetch_node_info method from FederationClient.
- Add clippy lint allowance for too many arguments in insert_federated_message function.
- Remove commented-out get_user_by_username function from user_repository.rs.

Author: AdamLBS