Pin HF Space to Python 3.12 + cap huggingface-hub<0.30

Gradio 4.44's oauth module imports `HfFolder`, which was removed in
huggingface-hub 0.30 — the Space's default image installs 0.30+, so
the app crashed at startup. Cap hf-hub for now.

Also pin the Space runtime to Python 3.12 so we stop chasing 3.13
regressions (already hit audioop removal; HfFolder was next; the old
gradio dep graph is riddled with them).

README.md

@@ -5,6 +5,7 @@ colorFrom: blue
 colorTo: purple
 sdk: gradio
 sdk_version: 4.44.0
+python_version: "3.12"
 app_file: app.py
 pinned: false
 license: mit

requirements.txt

@@ -33,4 +33,8 @@ pymatching>=2.2
 # on 3.13+ so the app starts. Harmless on 3.10–3.12.
 audioop-lts>=0.2.1; python_version >= "3.13"
 
+# Gradio 4.44's oauth module imports `HfFolder`, which was removed in
+# huggingface-hub 0.30. Pin below that until we can upgrade Gradio.
+huggingface-hub>=0.23,<0.30
+
 # CUDA-Q is installed separately on the Space (see README).