Parse seed for vLLM (#602)
When seed is set through model_args, for example:
```bash
"pretrained=deepseek-ai/DeepSeek-R1-Distill-Qwen-1.5B,seed=123,dtype=bfloat16,max_model_length=38768,gpu_memory_utilization=0.8,tensor_parallel_size=1"
``
it is parsed as a string attribute in `VLLMModelConfig`, leading to an error during LLM initialization:
```python
model = LLM(**self.model_args)
```
This PR ensures that seed is correctly cast to an integer before passing it to the model, preventing initialization errors.
Co-authored-by: Nathan Habib <30601243+NathanHB@users.noreply.github.com>
