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-libs/src/lettre/mod.rs

@@ -29,13 +29,7 @@ pub fn send_email(
 		.credentials(smtp_credentials)
 		.build();
 	match mailer.send(&email) {
-		Ok(_) => {
-			println!("Email sent successfully to {}", to);
-			Ok(())
-		}
-		Err(e) => {
-			println!("Failed to send email: {}", e);
-			Err(Box::new(e))
-		}
+		Ok(_) => Ok(()),
+		Err(e) => Err(Box::new(e)),
 	}
 }