fix: 메일 서비스 비동기처리

@async 에너테이션 추가

src/main/java/com/sch/chekirout/ChekiroutApplication.java

@@ -3,9 +3,11 @@
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
+import org.springframework.scheduling.annotation.EnableAsync;
 
 @EnableJpaAuditing
 @SpringBootApplication
+@EnableAsync
 public class ChekiroutApplication {
 
     //브랜치 확인

src/main/java/com/sch/chekirout/email/service/EmailService.java

@@ -12,6 +12,7 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.mail.javamail.JavaMailSender;
 import org.springframework.mail.javamail.MimeMessageHelper;
+import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -27,7 +28,8 @@ public class EmailService {
 
     private final EmailVerificationTokenRepository tokenRepository;
     private final UserRepository userRepository;
-
+
+    @Async
     public void sendVerificationEmail(String recipientEmail) {
 
         String token = generateEmailVerificationToken(recipientEmail);