It looks like you are trying to install Julia 1.6 or 1.7 on the "macos-latest" runners.
"macos-latest" now resolves to "macos-14", which run on Apple Silicon (aarch64) macOS machines.
Unfortunately, Julia 1.6 and 1.7 do not have native binaries available for Apple Silicon macOS.
Therefore, it is not possible to install Julia with the current constraints.
For instructions on how to fix this error, please see the following Discourse post: https://discourse.julialang.org/t/how-to-fix-github-actions-ci-failures-with-julia-1-6-or-1-7-on-macos-latest-and-macos-14/117019