ci: fix git safe.directory in NVHPC containers to silence ownership warnings

Author: sbryngelson

.github/workflows/test.yml

@@ -303,6 +303,7 @@ jobs:
           apt-get install -y cmake python3 python3-venv python3-pip \
                              libfftw3-dev libhdf5-dev hdf5-tools \
                              openmpi-bin libopenmpi-dev git
+          git config --global --add safe.directory /__w/MFC/MFC
 
       # --- Standard build + test ---
       - name: Build