Set python version

huggingface uses python 3.10 for spaces by default, but our version
of tokenizers isn't available as a wheel for that version, so specify a
version that has the old wheel available

TODO: upgrade stuff?

README.md

@@ -5,6 +5,7 @@ colorFrom: gray
 colorTo: pink
 sdk: gradio
 sdk_version: 5.33.0
+python_version: 3.9
 app_file: app.py
 pinned: false
 ---