Avalonia 适配Win7

  <PropertyGroup><ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally><!-- 默认使用高版本（Windows 10/11） --><SkiaSharpVersion>3.119.0</SkiaSharpVersion><SkiaSharpWin32Version>3.119.1</SkiaSharpWin32Version><!-- 如果是 Windows 7 系统，覆盖为兼容版本 --><SkiaSharpVersion Condition="$([System.Environment]::OSVersion.Version.Major) == 6 AND $([System.Environment]::OSVersion.Version.Minor) == 1">3.116.0</SkiaSharpVersion><SkiaSharpWin32Version Condition="$([System.Environment]::OSVersion.Version.Major) == 6 AND $([System.Environment]::OSVersion.Version.Minor) == 1">3.116.1</SkiaSharpWin32Version></PropertyGroup>