GPU Utilization zero when evaluating GGUFs through lm-evaluation

i'm enabling gpu-acceleration during installation as suggested in readme:
`CMAKE_ARGS="-DLLAMA_CUBLAS=on" FORCE_CMAKE=1
pip install 'llama-cpp-python[server]'`
Then activating the local server by:
`python3 -m llama_cpp.server --model models/7B/llama-model.gguf --n_gpu_layers -1`
and then finally using lm-evaluation for evaluating:

`lm_eval --model gguf --model_args base_url=http://localhost:8000 --tasks multimedqa`

....this just runs evaluation without using any GPU