Update Windows installation command for Astral UV

Current Windows command does not work on some machines such like mine. Copy and paste the command from Astral website to ensure the installation process go smoothly.

Author: Scriptwonder

README.md

@@ -73,7 +73,7 @@ MCP for Unity connects your tools using two components:
       curl -LsSf https://astral.sh/uv/install.sh | sh
 
       # Windows (PowerShell)
-      winget install Astral.Sh.Uv
+      winget install --id=astral-sh.uv  -e
 
       # Docs: https://docs.astral.sh/uv/getting-started/installation/
       ```