Pin gradio_client to fix build

There was an issue where the gradio_client and gradio versions got out of synch. This is something we fixed for new versions of gradio but not old ones.

You can see this working here: https://huggingface.co/spaces/freddyaboulton/Azure-OpenAI-QuickDemo

requirements.txt

@@ -1,3 +1,3 @@
 openai>=0.27.4
-gradio
+gradio_client==0.1.4
 requests