Remove "support hybrid search" from TODO list (#453)

## Motivation and Context (Why the change? What's the scenario?)

Now that Azure AI Search supports hybrid search (see
#428), the corresponding
item from the TODO list of **AzureAISearchMemory.cs** can be removed.

extensions/AzureAISearch/AzureAISearch/AzureAISearchMemory.cs

@@ -27,7 +27,6 @@ namespace Microsoft.KernelMemory.MemoryDb.AzureAISearch;
 /// Azure AI Search connector for Kernel Memory
 /// TODO:
 /// * support semantic search
-/// * support hybrid search
 /// * support custom schema
 /// * support custom Azure AI Search logic
 /// </summary>