Update audio duration on library scan (#707)

Source/DataLayer/EfClasses/Book.cs

@@ -106,6 +106,7 @@ namespace DataLayer
             ReplaceAuthors(authors);
             ReplaceNarrators(narrators);
         }
+
         public void UpdateTitle(string title, string subtitle)
         {
             Title = title?.Trim() ?? "";
@@ -113,6 +114,9 @@ namespace DataLayer
             _titleWithSubtitle = null;
         }
 
+        public void UpdateLengthInMinutes(int lengthInMinutes)
+            => LengthInMinutes = lengthInMinutes;
+
 		#region contributors, authors, narrators
 		internal HashSet<BookContributor> ContributorsLink { get; private set; }
 

Source/DtoImporterService/BookImporter.cs

@@ -149,6 +149,8 @@ namespace DtoImporterService
 		{
 			var item = importItem.DtoItem;
 
+			book.UpdateLengthInMinutes(item.LengthInMinutes);
+
 			// Update the book titles, since formatting can change
 			book.UpdateTitle(item.Title, item.Subtitle);