Update ci.yml

Author: sbryngelson

.github/workflows/ci.yml

@@ -70,11 +70,11 @@ jobs:
         run:  |
           module use /opt/nvidia/hpc_sdk/modulefiles/
           module load nvhpc/22.11
-          /bin/bash mfc.sh build -j $(nproc)
+          /bin/bash mfc.sh build -j 4
 
       - name: Test Suite
         run:  |
           module use /opt/nvidia/hpc_sdk/modulefiles/
           module load nvhpc/22.11
-          /bin/bash mfc.sh test  -j $(nproc)
+          /bin/bash mfc.sh test  -j 4