Comply with .net 8 for now

Source/Editor/GUI/Docking/FloatWindowDockPanel.cs

@@ -113,9 +113,12 @@ namespace FlaxEditor.GUI.Docking
 
         internal void UnlinkWindow()
         {
-            _window?.Window.Closing -= OnClosing;
-            _window?.Window.LeftButtonHit -= OnLeftButtonHit;
-            _window = null;
+            if (_window != null)
+            {
+                _window.Window.Closing -= OnClosing;
+                _window.Window.LeftButtonHit -= OnLeftButtonHit;
+                _window = null;
+            }
         }
 
         /// <inheritdoc />

Source/Tools/Flax.Build/Build/DotNet/DotNetSdk.cs

@@ -136,7 +136,7 @@ namespace Flax.Build
         /// <summary>
         /// The maximum SDK version.
         /// </summary>
-        public static Version MaximumVersion => new Version(10, 0);
+        public static Version MaximumVersion => new Version(8, 0);
 
         /// <inheritdoc />
         public override TargetPlatform[] Platforms