Update technology stack in README.md

Author: larama-C

README.md

@@ -170,26 +170,30 @@ ERD는 서비스의 핵심 도메인을 중심으로 관계형 데이터 구조
 
 ## Backend
 
-![Java](https://img.shields.io/badge/Java-17-007396?style=for-the-badge&logo=java&logoColor=white)
-![Spring Boot](https://img.shields.io/badge/Spring_Boot-3.0-6DB33F?style=for-the-badge&logo=springboot&logoColor=white)
+![Java](https://img.shields.io/badge/Java-21-007396?style=for-the-badge&logo=java&logoColor=white)
+![Spring Boot](https://img.shields.io/badge/Spring_Boot-3.5-6DB33F?style=for-the-badge&logo=springboot&logoColor=white)
+![Spring Security](https://img.shields.io/badge/Spring_Security-6DB33F?style=for-the-badge&logo=springsecurity&logoColor=white)
 ![Spring Data JPA](https://img.shields.io/badge/Spring_Data_JPA-6DB33F?style=for-the-badge)
-![Hibernate](https://img.shields.io/badge/Hibernate-59666C?style=for-the-badge&logo=hibernate&logoColor=white)
-![JWT](https://img.shields.io/badge/JWT-Authentication-000000?style=for-the-badge&logo=jsonwebtokens&logoColor=white)
+![Spring Data Redis](https://img.shields.io/badge/Spring_Data_Redis-DC382D?style=for-the-badge&logo=redis&logoColor=white)
 ![WebSocket](https://img.shields.io/badge/WebSocket-STOMP-010101?style=for-the-badge)
+![JWT](https://img.shields.io/badge/JWT-Authentication-000000?style=for-the-badge&logo=jsonwebtokens&logoColor=white)
+![Validation](https://img.shields.io/badge/Jakarta_Validation-FF6F00?style=for-the-badge)
 
 ## Database
 
 ![MySQL](https://img.shields.io/badge/MySQL-4479A1?style=for-the-badge&logo=mysql&logoColor=white)
-![Redis](https://img.shields.io/badge/Redis-DC382D?style=for-the-badge&logo=redis&logoColor=white)
+![H2](https://img.shields.io/badge/H2-Database-09476B?style=for-the-badge)
 
 ## Infrastructure
 
 ![AWS EC2](https://img.shields.io/badge/AWS_EC2-FF9900?style=for-the-badge&logo=amazon-ec2&logoColor=white)
+![AWS S3](https://img.shields.io/badge/AWS_S3-569A31?style=for-the-badge&logo=amazons3&logoColor=white)
 ![Docker](https://img.shields.io/badge/Docker-2496ED?style=for-the-badge&logo=docker&logoColor=white)
 
 ## DevOps
 
 ![GitHub Actions](https://img.shields.io/badge/GitHub_Actions-2088FF?style=for-the-badge&logo=githubactions&logoColor=white)
+![JaCoCo](https://img.shields.io/badge/JaCoCo-Test_Coverage-B22222?style=for-the-badge)
 
 ## Collaboration