Change access modifier to match constructor

Update MauiOxyTouchEventArgs.cs

* and update minimum OS versions of iOS and Mac
* we need to use $MauiVersion, in order to select the appropriate
  MAUI version for .NET 8 and .NET9, respectively
* also we fix one incompatibility in the source code

'Layout.LayoutChanged' is obsolete: 'Use SizeChanged.'

* and update minimum OS versions of iOS and Mac

'Application.MainPage.set' is obsolete: 'This property is deprecated. Initialize your application by overriding Application.CreateWindow rather than setting MainPage. To modify the root page in an active application, use Windows[0].Page for applications with a single window. For applications with multiple windows, use Application.Windows to identify and update the root page on the correct window.  Additionally, each element features a Window property, accessible when it's part of the current window.'

XamlC warning XC0022: Binding could be compiled to improve runtime performance if x:DataType is specified. See https://learn.microsoft.com/dotnet/maui/fundamentals/data-binding/compiled-bindings for more information.

(includes auto-formatting via prettier)

XamlC warning XC0024: Binding might be compiled incorrectly since the x:DataType annotation comes from an outer scope. Make sure you annotate all DataTemplate XAML elements with the correct x:DataType. See https://learn.microsoft.com/dotnet/maui/fundamentals/data-binding/compiled-bindings for more information.

Update to .NET 9

'SKPaint.Typeface' is obsolete: 'Use SKFont.Typeface instead.'
'SKPaint.GetFontMetrics(out SKFontMetrics)' is obsolete: 'Use SKFont.GetFontMetrics() instead.'
'SKPaint.TextAlign' is obsolete: 'Use SKTextAlign method overloads instead.'
'SKCanvas.DrawText(string, float, float, SKPaint)' is obsolete: 'Use DrawText(string text, float x, float y, SKTextAlign textAlign, SKFont font, SKPaint paint) instead.'
'CanvasExtensions.DrawShapedText(SKCanvas, SKShaper, string, float, float, SKPaint)' is obsolete: 'Use DrawShapedText(SKShaper shaper, string text, float x, float y, SKTextAlign textAlign, SKFont font, SKPaint paint) instead.'

warning CS0618: 'SKPaint.FilterQuality' is obsolete: 'Use SKSamplingOptions instead.'
warning CS0618: 'SKFilterQuality' is obsolete: 'Use SKSamplingOptions instead.'

* by commenting out code
* warning CS0618: 'SKPaint.TextEncoding' is obsolete: 'Use SKTextEncoding method overloads instead.'
* note: SKPaint.TextEncoding is not set anywhere,
  i.e. it always stays at the default value (which per documentation is Utf8)

update SkiaSharp to 3.116.1