Fix Shoonya API OAuth Login

I’m stuck on the authentication step while integrating the Shoonya trading API with a small Python script. The login sequence stops at getOAuth creation and returns an error before any tokens are issued, so the session never starts.

What I need from you is clear:
• Review my existing Python code that calls getOAuth.
• Identify why the OAuth request fails and correct it—whether it’s the request format, headers, or any missing parameter.
• Return a clean, well-commented snippet (or module) that successfully authenticates and delivers the expected access token.

Please test the fix with the live Shoonya endpoint so I can drop the working function straight into my script. A short note explaining the change will be enough for me to follow the logic.