Make cubin compilation arch explicit in fatbin fixture

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: leofang

cuda_core/tests/test_module.py

@@ -117,7 +117,7 @@ def get_saxpy_fatbin(init_cuda):
     second_arch = "75" if arch != "75" else "80"
 
     # Compile to cubin for current device arch
-    prog = Program(SAXPY_KERNEL, code_type="c++")
+    prog = Program(SAXPY_KERNEL, code_type="c++", options=ProgramOptions(arch=f"sm_{arch}"))
     mod = prog.compile(
         "cubin",
         name_expressions=("saxpy<float>", "saxpy<double>"),