Update the test image

.github/workflows/tests.yml

@@ -10,6 +10,7 @@ jobs:
   unittest:
     name: unittest
     runs-on: ubuntu-24.04
+    container: seissol/gha-cpu:davschneller-gpu-image
     strategy:
       fail-fast: false
       matrix:
@@ -36,7 +37,6 @@ jobs:
           sudo apt-get install -y software-properties-common
           sudo add-apt-repository ppa:deadsnakes/ppa
           sudo apt-get update -y
-          sudo apt-get install -y libomp-dev libopenmpi-dev openmpi-bin openmpi-common ninja-build gfortran openmpi-bin openmpi-common libopenmpi-dev libnetcdf-dev libnuma-dev cmake
           sudo apt-get install -y cxxtest
 
       - name: build