github-copilot provder is not working

[Matheus-Garbelini]

Description

When configuring github copilot as provider and correct access token, I get the following error:

model failed: error receiving from stream: HTTP 400: POST "https://api.githubcopilot.com/chat/completions":
400 Bad Request

Configuration file used

agents:
  root:
    model: github-copilot/gemini-3.1-pro-preview
    skills: true
    toolsets:
      - type: filesystem

[elgreco247]

see #2471