refactor: 회원 탈퇴 API HTTP Method를 PATCH에서 DELETE로 변경 (#311)

* refactor: 회원 탈퇴 API HTTP Method를 PATCH에서 DELETE로 변경

* chore: 불필요한 import 제거

Author: Gyuhyeok99

src/main/java/com/example/solidconnection/auth/controller/AuthController.java

@@ -26,7 +26,7 @@
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.Authentication;
-import org.springframework.web.bind.annotation.PatchMapping;
+import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -102,7 +102,7 @@ public ResponseEntity<Void> signOut(
         return ResponseEntity.ok().build();
     }
 
-    @PatchMapping("/quit")
+    @DeleteMapping("/quit")
     public ResponseEntity<Void> quit(
             @AuthorizedUser SiteUser siteUser,
             Authentication authentication // todo: #299를 작업하며 인자를 (Authentication authentication)만 받도록 수정해야 함