Reintroduce OpenMPI tests

Author: RemiLehe

.github/workflows/unix-openmpi.yml

@@ -0,0 +1,38 @@
+name: Unix-OpenMPI
+
+on:
+  pull_request:
+  # Run daily at midnight (UTC).
+  schedule:
+    - cron: '0 0 * * *'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.10', 3.11]
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: conda-incubator/setup-miniconda@v3
+      name: Setup conda
+      with:
+        auto-update-conda: true
+        activate-environment: testing
+        auto-activate-base: false
+        channels: defaults
+        channel-priority: true
+        python-version: ${{ matrix.python-version }}
+
+    - shell: bash -l {0}
+      name: Install dependencies
+      run: |
+        conda install numpy pandas pytorch cpuonly -c pytorch
+        conda install -c conda-forge mpi4py openmpi
+        pip install .[test]
+    - shell: bash -l {0}
+      name: Run unit tests with openMPI
+      run: |
+        python -m pytest tests/
+        mpirun -np 3 --oversubscribe python -m pytest --with-mpi tests/test_grid_sampling_mpi.py