test: set class to not be sealed to allow mocking

Velaptor/Graphics/RenderBatchReactable.cs

@@ -12,6 +12,6 @@ namespace Velaptor.Graphics;
 /// <inheritdoc cref="IRenderBatchReactable{TBatchItem}"/>
 /// <typeparam name="TBatchItem">The type of batch item to send.</typeparam>
 [SuppressMessage("ReSharper", "RedundantTypeDeclarationBody", Justification = "Intentional")]
-internal sealed class RenderBatchReactable<TBatchItem> : PushReactable<Memory<RenderItem<TBatchItem>>>, IRenderBatchReactable<TBatchItem>
+internal class RenderBatchReactable<TBatchItem> : PushReactable<Memory<RenderItem<TBatchItem>>>, IRenderBatchReactable<TBatchItem>
 {
 }