[llvm] [GitHub] Fix slow sccache install on macOS by upgrading macOS version (PR #77165)

[Craig Hesling via llvm-commits]

linux4life798 wrote:

Test run with `macOS-latest`, but with the `PKG_CONFIG_PATH` env var removed.

https://github.com/linux4life798/llvm-project/actions/runs/7428652707/job/20216260090

https://github.com/llvm/llvm-project/pull/77165