Fix fortran mpi module in mac CI

Author: atmyers

.github/workflows/dependencies/dependencies_mac.sh

@@ -9,10 +9,16 @@ set -eu -o pipefail
 
 brew update
 brew install gfortran || true
-brew install libomp || true
-brew install open-mpi || true
-brew install ccache || true
 
 # verify installation
 gfortran-14 --version
 otool -L $(which gfortran-14)
+
+# make sure to install Open MPI with the correct Fortran compiler
+export FC=$(which gfortran-14)
+export F77=$FC
+export F90=$FC
+
+brew install libomp || true
+brew install open-mpi || true
+brew install ccache || true