Fix CI

To run CI on DAS-6, the configuration now needs to specify das6-gpu instead of das6. The CUDA version used in CI has been updated to version 12.2.1, since CUDA 11.5.1 is no longer available.

scripts/load-modules.sh

 module load spack/9.4.0
-module load cuda/11.5.1
+module load cuda/12.2.1