Fix BitmapInterpolationMode default value

src/Skia/Avalonia.Skia/SkiaSharpExtensions.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Skia
         {
             switch (interpolationMode)
             {
+                case BitmapInterpolationMode.Unspecified:
                 case BitmapInterpolationMode.LowQuality:
                     return SKFilterQuality.Low;
                 case BitmapInterpolationMode.MediumQuality:
@@ -20,7 +21,6 @@ namespace Avalonia.Skia
                 case BitmapInterpolationMode.HighQuality:
                     return SKFilterQuality.High;
                 case BitmapInterpolationMode.None:
-                case BitmapInterpolationMode.Unspecified:
                     return SKFilterQuality.None;
                 default:
                     throw new ArgumentOutOfRangeException(nameof(interpolationMode), interpolationMode, null);

src/Windows/Avalonia.Direct2D1/Media/DrawingContextImpl.cs

@@ -149,6 +149,7 @@ namespace Avalonia.Direct2D1.Media
         {
             switch (interpolationMode)
             {
+                case BitmapInterpolationMode.Unspecified:
                 case BitmapInterpolationMode.LowQuality:
                     return InterpolationMode.Linear;
                 case BitmapInterpolationMode.MediumQuality:
@@ -156,7 +157,6 @@ namespace Avalonia.Direct2D1.Media
                 case BitmapInterpolationMode.HighQuality:
                     return InterpolationMode.HighQualityCubic;
                 case BitmapInterpolationMode.None:
-                case BitmapInterpolationMode.Unspecified:
                     return InterpolationMode.NearestNeighbor;
                 default:
                     throw new ArgumentOutOfRangeException(nameof(interpolationMode), interpolationMode, null);