Revert "ci: remove multi-threading in nvcc compile flags (#229)" (#230)

This reverts commit f1da148.

Author: yzh119

python/setup.py

@@ -394,6 +394,8 @@ def __init__(self, *args, **kwargs) -> None:
                 "nvcc": [
                     "-O3",
                     "-std=c++17",
+                    "--threads",
+                    "8",
                     "-Xfatbin",
                     "-compress-all",
                 ],