fix: Default max tokens to None for OpenAI frontend.

python/openai/openai_frontend/schemas/openai.py

@@ -103,7 +103,7 @@ class CreateCompletionRequest(BaseModel):
         description="Include the log probabilities on the `logprobs` most likely output tokens, as well the chosen tokens. For example, if `logprobs` is 5, the API will return a list of the 5 most likely tokens. The API will always return the `logprob` of the sampled token, so there may be up to `logprobs+1` elements in the response.\n\nThe maximum value for `logprobs` is 5.\n",
     )
     max_tokens: Optional[conint(ge=0)] = Field(
-        16,
+        None,
         description="The maximum number of [tokens](/tokenizer) that can be generated in the completion.\n\nThe token count of your prompt plus `max_tokens` cannot exceed the model's context length. [Example Python code](https://cookbook.openai.com/examples/how_to_count_tokens_with_tiktoken) for counting tokens.\n",
         examples=[16],
     )