Fix HuggingFace Spaces deployment: simplify launch config and constrain Gradio version

app.py

@@ -691,5 +691,4 @@ with gr.Blocks(title="ToGMAL - Difficulty Analyzer + Chat", css="""
             )
 
 if __name__ == "__main__":
-    port = int(os.environ.get("GRADIO_SERVER_PORT", 7860))
-    demo.launch(server_name="0.0.0.0", server_port=port)
+    demo.launch()

requirements.txt

@@ -8,5 +8,5 @@ joblib>=1.3
 sentence-transformers>=2.2.0
 chromadb>=0.4.0
 datasets>=2.14.0
-gradio>=4.0.0
+gradio>=4.0.0,<5.0.0
 huggingface-hub>=0.19.0