Some of the tests are flaky with 4 MPI ranks oversubscribed. Try with 2

Author: sbird

.github/workflows/main.yaml

@@ -48,7 +48,7 @@ jobs:
     - name: MPI Unit tests
       run: |
         cd nbodykit
-        mpirun -n 4 --oversubscribe python -m pytest --with-mpi
+        mpirun -n 2 python -m pytest --with-mpi
     - name: Store the distribution packages
       if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.10' #Only do this once!
       uses: actions/upload-artifact@v4