bugfix: only use sm90 group gemm when torch cuda >= 12.3 (#699)

wgmma is only available for cuda 12.3 or later, turn to use sm80 version
when torch.cuda version is lower.

cc @xslingcn

flashinfer/utils.py

@@ -257,7 +257,7 @@ def get_cuda_stream(device: torch.device) -> int:
 
 def determine_gemm_backend(device: torch.device) -> str:
     major, _ = get_compute_capability(device)
-    if major >= 9:
+    if major >= 9 and torch.version.cuda >= "12.3":
         return "sm90"
     else:
         return "sm80"