use spack from the /home/pruvost of gitlab-runner user, to avoid possible locks

.gitlab-ci.yml

@@ -17,7 +17,7 @@ starpu-simgrid:
     - git submodule update
     - mkdir build
     - cd build
-    - . /home/ci/spack/share/spack/setup-env.sh
+    - . $HOME/spack/share/spack/setup-env.sh
     - spack load hwloc && spack load fxt && spack load simgrid && spack load starpu
     - cmake .. -DCHAMELEON_SIMULATION=ON -DCHAMELEON_USE_CUDA=ON -DCHAMELEON_USE_MAGMA=OFF -DCHAMELEON_USE_MPI=OFF
     - make -j2