Fix flashinfer >= 0.0.3 compat

[Qubitium]

sglang currently is not compatible with latest flashinfer or vice-versa:

Blocking Error with flashinfer 0.0.3

Exception in ModelRpcClient:
Traceback (most recent call last):
  File "/root/miniconda3/lib/python3.11/site-packages/sglang/srt/managers/router/model_rpc.py", line 184, in exposed_step
    self.forward_step()
  File "/root/miniconda3/lib/python3.11/site-packages/torch/utils/_contextlib.py", line 115, in decorate_context
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/root/miniconda3/lib/python3.11/site-packages/sglang/srt/managers/router/model_rpc.py", line 211, in forward_step
    self.forward_decode_batch(self.running_batch)
  File "/root/miniconda3/lib/python3.11/site-packages/sglang/srt/managers/router/model_rpc.py", line 505, in forward_decode_batch
    next_token_ids, _ = batch.sample(logits)
                        ^^^^^^^^^^^^^^^^^^^^
  File "/root/miniconda3/lib/python3.11/site-packages/sglang/srt/managers/router/infer_batch.py", line 476, in sample
    sampled_index = torch.multinomial(probs_sort, num_samples=1)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: probability tensor contains either `inf`, `nan` or element < 0

Edit: blocking error fixed in flashinfer upstream. Pending flashinfer 0.0.4 very soon.

[Qubitium]

@hnyls2002 PR is ready for merge. Please review. Tested with both flashinfer 0.0.3-dev (master with batch bug fix) and 0.0.2.