Merge pull request #1860 from AvaloniaUI/fixes/1856-slider-value-not-updated

fix slider not updating value.

src/Avalonia.Controls/Slider.cs

@@ -171,11 +171,7 @@ namespace Avalonia.Controls
         /// <param name="value">Value that want to snap to closest Tick.</param>
         private void MoveToNextTick(double value)
         {
-            double next = SnapToTick(Math.Max(Minimum, Math.Min(Maximum, value)));
-            if (next != value)
-            {
-                Value = next;
-            }
+            Value = SnapToTick(Math.Max(Minimum, Math.Min(Maximum, value)));
         }
 
         /// <summary>
@@ -194,4 +190,4 @@ namespace Avalonia.Controls
             return value;
         }
     }
-}
+}