Update command to test

Author: rohanbabbar04

.github/workflows/build.yml

@@ -43,4 +43,4 @@ jobs:
       - name: Install pylops-mpi
         run: pip install .
       - name: Testing using pytest-mpi
-        run: mpiexec -n ${{ matrix.rank }} pytest tests/test_solver.py --with-mpi
+        run: mpiexec -n ${{ matrix.rank }} pytest tests/ --with-mpi -v -x