Include correct thought signature in functionCall parts

[manthanabc]

⏺ [06:00:49] ERROR: POST https://generativelanguage.googleapis.com/v1beta/openai/chat/completions

Caused by:
0: 400 Bad Request Reason: [{
"error": {
"code": 400,
"message": "Function call is missing a thought_signature in functionCall parts. This is required for tools to work correctly, and missing thought_signature may lead to degraded model performance. Additional data, function call default_api:shell , position 2. Please refer to https://ai.google.dev/gemini-api/docs/thought-signatures for more details.",
"status": "INVALID_ARGUMENT"
}
}
]
1: Invalid Status Code: 400