Got rid of OMPI_UNIVERSE thing

Author: brownbaerchen

.github/workflows/ci_pipeline.yml

@@ -214,7 +214,6 @@ jobs:
           python -c "import gusto; print(f'gusto module: {gusto}')"
       - name: run pytest
         run: |
-          export OMPI_UNIVERSE_SIZE=64
           . venv-pySDC/bin/activate
           firedrake-clean
           cd ./pySDC