More workflow adjustment

Author: sbird

.github/workflows/main.yaml

@@ -47,6 +47,7 @@ jobs:
         python -m pytest --with-mpi
     - name: MPI Unit tests
       run: |
+        cd nbodykit
         mpirun -n 4 --oversubscribe python -m pytest --with-mpi
     - name: Store the distribution packages
       if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.10' #Only do this once!