Pin gradio 6.20.0 and scope OAuth to inference-api only

- sdk_version 6.20.0; requirements gradio>=6.20.0
- hf_oauth: true with a single hf_oauth_scopes entry (inference-api),
since the workflow only calls the model via the HF Inference API and
needs no repo read/write/gated/manage access

README.md

@@ -4,10 +4,12 @@ emoji: 🖼️
 colorFrom: yellow
 colorTo: yellow
 sdk: gradio
-sdk_version: 6.1.0
+sdk_version: 6.20.0
 app_file: app.py
 pinned: true
 hf_oauth: true
+hf_oauth_scopes:
+  - inference-api
 ---
 
 # Z-Image-Turbo (Gradio Workflow)

requirements.txt

@@ -1,3 +1,3 @@
-gradio>=6.1
+gradio>=6.20.0
 huggingface_hub>=0.36.0
 gradio[mcp]