fix setup for sgl kernel (#2917)

sgl-kernel/setup.py

@@ -15,6 +15,7 @@ def get_version():
 
 def update_wheel_platform_tag():
     wheel_dir = Path("dist")
+    if wheel_dir.exists() and wheel_dir.is_dir():
         old_wheel = next(wheel_dir.glob("*.whl"))
         new_wheel = wheel_dir / old_wheel.name.replace(
             "linux_x86_64", "manylinux2014_x86_64"