🐛 fix: @controller -> @RestController 수정

Author: jiwon1217

backend/src/main/java/io/f1/backend/domain/user/api/UserController.java

@@ -12,13 +12,13 @@
 
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
-import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
 
-@Controller
+@RestController
 @RequiredArgsConstructor
 @RequestMapping("/user/me")
 public class UserController {