avalonia: Updated InABox.Avalonia.Platform.Android to .NET 9

InABox.Avalonia.Platform.Android/InABox.Avalonia.Platform.Android.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net8.0-android</TargetFramework>
+        <TargetFramework>net9.0-android</TargetFramework>
         <SupportedOSPlatformVersion>34</SupportedOSPlatformVersion>
         <TargetPlatformSdkRootOverride>34</TargetPlatformSdkRootOverride>
         <ImplicitUsings>enable</ImplicitUsings>