Update cmake-single-platform.yml

Author: niklas-uhl

.github/workflows/cmake-single-platform.yml

@@ -21,6 +21,7 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
+    - uses: mpi4py/setup-mpi@v1
 
     - name: Configure CMake
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.