test with V8 on macOS/x86_64 is not reusing cache

[PiotrSikora]

It looks that sha256sum was removed (or possibly replaced with gsha256sum?), which broke cache-key evaluation:

echo "::set-output name=uniq::$(bazel query --output build //external:v8 | grep -E 'sha256|commit' | cut -d\" -f2)-$(echo  | sha256sum)"
[...]
/Users/runner/work/_temp/4a550a5e-9186-4641-9bff-d391171da246.sh: line 1: sha256sum: command not found

cc @mpwarres

[mpwarres]

Interesting--I wonder if it's always been that way? sha256sum doesn't exist on MacOS (e.g. ESGF/esg-search#84), but can be done via shasum -a 256.

[PiotrSikora]

Actually, it looks that the cache entry exists and it's downloaded, but it doesn't speed up the build process, so something else is broken.

As for sha256sum, it's possible that it was always broken, since it was added to differentiate between sanitizer builds, and we only use them on Linux, so this should be only noise on macOS.