Fix invalid colorFrom causing build failure when duplicating space

The colorFrom field, which determines one of the colours of the [thumbnail gradient](https://huggingface.co/docs/hub/spaces-config-reference) is currently set to an invalid colour 'white'. This causes the build to fail when duplicating the space.

Changed it to the nearest valid colour 'gray', but any of the other valid colours will fix the issue.

README.md

@@ -7,7 +7,7 @@ tags:
   - "LLMs"
 app_file: "app.py"
 emoji: 🎵
-colorFrom: white
+colorFrom: gray
 colorTo: blue
 sdk: gradio
 sdk_version: 3.34.0