fix: DisplayRange is not updated when text diff view is opened for the first time

src/Views/TextDiffView.axaml.cs

@@ -619,6 +619,7 @@ namespace SourceGit.Views
             TextArea.TextView.VisualLinesChanged += OnTextViewVisualLinesChanged;
 
             UpdateTextMate();
+            OnTextViewVisualLinesChanged(null, null);
         }
 
         protected override void OnUnloaded(RoutedEventArgs e)