fix: 라이브 리스트 API

- 라이브 시작 시간 UTC 추가

src/main/kotlin/kr/co/vividnext/sodalive/live/room/GetRoomListResponse.kt

@@ -5,6 +5,7 @@ data class GetRoomListResponse(
     val title: String,
     val content: String,
     val beginDateTime: String,
+    val beginDateTimeUtc: String,
     val numberOfParticipate: Int,
     val numberOfPeople: Int,
     val coverImageUrl: String,

src/main/kotlin/kr/co/vividnext/sodalive/live/room/LiveRoomService.kt

@@ -176,11 +176,15 @@ class LiveRoomService(
                             .withLocale(Locale.KOREAN)
                     )
 
+                val beginDateTimeUtc = it.beginDateTime
+                    .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
+
                 GetRoomListResponse(
                     roomId = it.id!!,
                     title = it.title,
                     content = it.notice,
                     beginDateTime = beginDateTime,
+                    beginDateTimeUtc = beginDateTimeUtc,
                     numberOfParticipate = (roomInfo?.listenerCount ?: 0) +
                         (roomInfo?.speakerCount ?: 0) +
                         (roomInfo?.managerCount ?: 0),