Update cis.

Author: vehre

.github/workflows/ci.yml

@@ -10,17 +10,22 @@ jobs:
 
     env:
       FC: gfortran
-      GCC_V: 11
+      GCC_V: 13
 
     steps:
     - name: Checkout code
       uses: actions/checkout@v3
 
     - name: Install Dependencies
       run: |
-        sudo apt install -y gfortran-${GCC_V} cmake mpich
+        sudo apt install -y gfortran-${GCC_V} cmake
         sudo update-alternatives --install /usr/bin/gfortran gfortran /usr/bin/gfortran-${GCC_V} 100
 
+    - name: Setup MPI
+      uses: mpi4py/setup-mpi@v1
+      with:
+        mpi: mpich
+
     - name: Build and Test
       run: |
         mkdir build