Add no-gpu option for non-GPU device tests

Author: sbryngelson

.github/workflows/frontier/test.sh

@@ -16,5 +16,5 @@ fi
 if [ "$job_device" = "gpu" ]; then
     ./mfc.sh test -a --rdma-mpi --max-attempts 3 -j $ngpus $device_opts -- -c frontier
 else
-    ./mfc.sh test -a --max-attempts 3 -j 32 -- -c frontier
+    ./mfc.sh test -a --max-attempts 3 -j 32 --no-gpu -- -c frontier
 fi