Revert DTO, Changed messagepackprotocol again.

LightlessSyncAPI/Dto/Group/GroupPruneSettingsDto.cs

@@ -1,6 +1,7 @@
 using LightlessSync.API.Data;
+using MessagePack;
 
-namespace LightlessSync.API.Dto.Group
-{
-    public record GroupPruneSettingsDto(GroupData Group, bool AutoPruneEnabled, int AutoPruneDays);
-}
+namespace LightlessSync.API.Dto.Group;
+
+[MessagePackObject(keyAsPropertyName: true)]
+public record GroupPruneSettingsDto(GroupData Group, bool AutoPruneEnabled, int AutoPruneDays);