scripts: fix compare-llama-bench commit hash logic#11891

JohannesGaessler merged 1 commit intoggml-org:masterggml-org/llama.cpp:masterfrom

JohannesGaessler:clb-fix-hexsha-lengthJohannesGaessler/llama.cpp:clb-fix-hexsha-lengthCopy head branch name to clipboard