try install libopenmp

Author: ljgray

.github/workflows/main.yml

@@ -49,7 +49,7 @@ jobs:
             install: install -y libopenmpi-dev openmpi-bin libhdf5-serial-dev
           - os: macos-latest
             installer: brew
-            install: install open-mpi
+            install: install open-mpi libomp
 
     runs-on: ${{ matrix.os }}