Fix HF Spaces build: pin Python 3.10 for TF 2.15.0 compatibility

HF Spaces defaults to Python 3.13 which only supports TF 2.20+.
Pin python_version to 3.10 in the Space config so TF 2.15.0 installs.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -5,6 +5,7 @@ colorFrom: blue
 colorTo: purple
 sdk: gradio
 sdk_version: "4.44.1"
+python_version: "3.10"
 app_file: app.py
 pinned: false
 license: mit