콘텐츠 메인 항목 - 사용하지 않는 isAdult 제거

src/main/kotlin/kr/co/vividnext/sodalive/content/main/GetAudioContentMainItem.kt

@@ -7,7 +7,6 @@ data class GetAudioContentMainItem @QueryProjection constructor(
     @JsonProperty("contentId") val contentId: Long,
     @JsonProperty("coverImageUrl") val coverImageUrl: String,
     @JsonProperty("title") val title: String,
-    @JsonProperty("isAdult") val isAdult: Boolean,
     @JsonProperty("creatorId") val creatorId: Long,
     @JsonProperty("creatorProfileImageUrl") val creatorProfileImageUrl: String,
     @JsonProperty("creatorNickname") val creatorNickname: String