Python: default temp should be null, to match dotnet, and utilize OpenAI's default value.

[moonbox3]

Describe the bug
In comparing the dotnet and python request body, we have different default temp values. Python defaults to 0.0 whereas dotnet defaults to 1, which is OpenAI's default value. https://platform.openai.com/docs/api-reference/completions/create#completions-create-temperature

Python:

{
    "messages":
    [
        {
            "role": "user",
            "content": "Can you help me tell the time in Seattle right now?"
        }
    ],
    "model": "gpt-3.5-turbo-1106",
    "frequency_penalty": 0.0,
    "logit_bias": {},
    "max_tokens": 256,
    "n": 1,
    "presence_penalty": 0.0,
    "stream": false,
    "temperature": 0.0,
    "top_p": 1.0
}

Versus .net:

{
  "messages": [
    {
      "content": "Can you help me tell the time in Seattle right now?",
      "role": "user"
    }
  ],
  "temperature": 1,
  "top_p": 1,
  "n": 1,
  "presence_penalty": 0,
  "frequency_penalty": 0,
  "model": "Dummy"
}

[moonbox3]

Dupe of #6225. Closing.