Fix for #7284 (#15734)

Comparing WindowVersion with Windows8_1 instead of Windows8

Co-authored-by: Max Katz <[email protected]>

src/Windows/Avalonia.Win32/FramebufferManager.cs

@@ -88,7 +88,7 @@ namespace Avalonia.Win32
 
         private Vector GetCurrentDpi()
         {
-            if (UnmanagedMethods.ShCoreAvailable && Win32Platform.WindowsVersion > PlatformConstants.Windows8)
+            if (UnmanagedMethods.ShCoreAvailable && Win32Platform.WindowsVersion >= PlatformConstants.Windows8_1)
             {
                 var monitor =
                     UnmanagedMethods.MonitorFromWindow(_hwnd, UnmanagedMethods.MONITOR.MONITOR_DEFAULTTONEAREST);

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -937,7 +937,7 @@ namespace Avalonia.Win32
 
             RegisterTouchWindow(_hwnd, 0);
 
-            if (ShCoreAvailable && Win32Platform.WindowsVersion > PlatformConstants.Windows8)
+            if (ShCoreAvailable && Win32Platform.WindowsVersion >= PlatformConstants.Windows8_1)
             {
                 var monitor = MonitorFromWindow(
                     _hwnd,