fix: Vote 저장 시 FE로부터 받은 KST 종료 시각을 UTC로 변환해 저장 (#79)

Author: soonge2

src/main/java/com/moa/moa_server/domain/vote/service/VoteService.java

@@ -90,7 +90,7 @@ public Long createVote(Long userId, VoteCreateRequest request) {
                 group,
                 request.content(),
                 imageUrl,
-                request.closedAt(),
+                request.closedAt().minusHours(9),
                 request.anonymous(),
                 adminVote
         );