[Merge] Merge pull request #355 from Team-WSS/fix/#354

[FIX] 피드 수정된 이미지를 불러올 수 없는 문제 수정

Author: GiJungPark

src/main/java/org/websoso/WSSServer/service/FeedService.java

@@ -111,7 +111,7 @@ public void createFeed(User user, FeedCreateRequest request, FeedImageCreateRequ
     public void updateFeed(Long feedId, FeedUpdateRequest request, FeedImageUpdateRequest imagesRequest) {
         Feed feed = getFeedOrException(feedId);
 
-        List<FeedImage> oldImages = feed.getImages();
+        List<FeedImage> oldImages = new ArrayList<>(feed.getImages());
 
         if (request.novelId() != null && feed.isNovelChanged(request.novelId())) {
             novelService.getNovelOrException(request.novelId());