Added a UTC timestamp for reading history events (#3640)

API/DTOs/Statistics/ReadHistoryEvent.cs

@@ -13,6 +13,7 @@ public class ReadHistoryEvent
     public int SeriesId { get; set; }
     public required string SeriesName { get; set; } = default!;
     public DateTime ReadDate { get; set; }
+    public DateTime ReadDateUtc { get; set; }
     public int ChapterId { get; set; }
     public required float ChapterNumber { get; set; } = default!;
 }