Mirgecom downstream CI: Use mpi4py from conda

Author: inducer

.github/workflows/ci.yml

@@ -148,17 +148,16 @@ jobs:
 
                 if test "$DOWNSTREAM_PROJECT" = "mirgecom"; then
                     # can't turn off MPI in mirgecom
-                    sudo apt-get update
-                    sudo apt-get install openmpi-bin libopenmpi-dev
                     export CONDA_ENVIRONMENT=conda-env.yml
                     export CISUPPORT_PARALLEL_PYTEST=no
+                    echo "- mpi4py" >> "$CONDA_ENVIRONMENT"
                 else
                     sed -i "/mpi4py/ d" requirements.txt
                 fi
 
                 build_py_project_in_conda_env
                 test_py_project
-                
+
                 if [[ "$DOWNSTREAM_PROJECT" = "meshmode" ]]; then
                     python ../examples/simple-dg.py --lazy
                 fi