Remove invalid sdk_version from README frontmatter

The version 4.50.0 doesn't exist. Let HF use version from requirements.txt.

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

README.md

@@ -4,7 +4,6 @@ emoji: 🎯
 colorFrom: blue
 colorTo: purple
 sdk: gradio
-sdk_version: "4.50.0"
 app_file: app.py
 pinned: false
 tags: