feat(batch): make OpenAI interface extend Batch interface (#433)

Author: mXaln

openai-client/src/commonMain/kotlin/com.aallam.openai.client/OpenAI.kt

@@ -11,7 +11,7 @@ import kotlin.time.Duration.Companion.seconds
  * OpenAI API.
  */
 public interface OpenAI : Completions, Files, Edits, Embeddings, Models, Moderations, FineTunes, Images, Chat, Audio,
-    FineTuning, Assistants, Threads, Runs, Messages, VectorStores, AutoCloseable
+    FineTuning, Assistants, Threads, Runs, Messages, VectorStores, Batch, AutoCloseable
 
 /**
  * Creates an instance of [OpenAI].