Use thread-safe version of gpu-lite

[Luthaf]

@RMeli, do we have access to multiple GPU on the CSCS-CI, or do I need to change some setting?

[RMeli]

@Luthaf yes, CI runs on Alps so you can have multiple GPUs and multiple nodes. Currently we ask for one node and run with a single task:

vesin/ci/cscs.yaml

Lines 31 to 33 in 82302f2

	SLURM_JOB_NUM_NODES: 1
	SLURM_PARTITION: normal
	SLURM_NTASKS: 1

We are working on node sharing, but for the time being you get a full node and therefore all 4 GPUs are available.