Add comprehensive tests for mentor repository and authentication

- 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.

imphnen-utils/src/response_format.rs

@@ -1,7 +1,7 @@
 use axum::{
+	Json,
 	http::StatusCode,
 	response::{IntoResponse, Response},
-	Json,
 };
 use serde::Serialize;
 use serde_json::json;