fixes: Replace CS8600 warning suppression with null-forgiving operator

src/Avalonia.Base/Data/BindingValue.cs

@@ -247,9 +247,7 @@ namespace Avalonia.Data
                 UnsetValueType _ => Unset,
                 DoNothingType _ => DoNothing,
                 BindingNotification n => n.ToBindingValue().Cast<T>(),
-#pragma warning disable CS8600 // Converting null literal or possible null value to non-nullable type.
-                _ => new BindingValue<T>((T)value)
-#pragma warning restore CS8600 // Converting null literal or possible null value to non-nullable type.
+                _ => new BindingValue<T>((T)value!)
             };
         }
 

src/Avalonia.Styling/Styling/Setter.cs

@@ -101,11 +101,7 @@ namespace Avalonia.Styling
                 data.result = new PropertySetterInstance<T>(
                     data.target,
                     property,
-#pragma warning disable CS8600 // Converting null literal or possible null value to non-nullable type.
-#pragma warning disable CS8604 // Possible null reference argument.
-                    (T)data.value);
-#pragma warning restore CS8604 // Possible null reference argument.
-#pragma warning restore CS8600 // Converting null literal or possible null value to non-nullable type.
+                    (T)data.value!);
             }
         }
 
@@ -132,11 +128,7 @@ namespace Avalonia.Styling
                 data.result = new PropertySetterInstance<T>(
                     data.target,
                     property,
-#pragma warning disable CS8600 // Converting null literal or possible null value to non-nullable type.
-#pragma warning disable CS8604 // Possible null reference argument.
-                    (T)data.value);
-#pragma warning restore CS8604 // Possible null reference argument.
-#pragma warning restore CS8600 // Converting null literal or possible null value to non-nullable type.
+                    (T)data.value!);
             }
         }