feat(auth): Add error handling for authentication and validation errors
feat(auth): Implement default role assignment for new users in Google OAuth flow
feat(utils): Introduce CSRF token generation and validation utilities
fix(dependencies): Update Cargo.toml to include base64 and sha2 dependencies
- Implemented tests for creating, retrieving, updating, and deleting mentors in `mentor_repository_test.rs`.
- Added tests for user authentication, including successful login, invalid email formats, and inactive users in `auth_login_tests.rs`.
- Created a mock test environment setup in `mock_test.rs` to facilitate database operations during tests.
- Updated module structure to include new test files for mentors and authentication.
- Ensured cleanup of the database after tests to maintain isolation and prevent side effects.