CI: Cache homebrew deps

[andy5995]

No description provided.

[andy5995]

Some things can be cached: https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows

I'm not sure if this one of them. I may give up on this.

Run actions/cache@v3
  with:
    path: /usr/local/Cellar
  /usr/local/opt
  
    key: brew-cache-macOS-0305e7d1fec85c978b1856b2aa2011752ada64d9eecb4ea0b966dca8e14672c8
    restore-keys: brew-cache-macOS-
  
    enableCrossOsArchive: false
    fail-on-cache-miss: false
    lookup-only: false
  env:
    LDFLAGS: -L/opt/homebrew/opt/llvm/lib
    CPPFLAGS: -I/opt/homebrew/opt/llvm/include
Cache Size: ~48 MB (50068404 B)
/opt/homebrew/bin/gtar -xf /Users/runner/work/_temp/5f930b4a-1c1e-4b49-8379-0280d258360b/cache.tzst -P -C /Users/runner/work/vs-fltk/vs-fltk --delay-directory-restore --use-compress-program unzstd
Received 50068404 of 50068404 (100.0%), 47.6 MBs/sec
/opt/homebrew/bin/gtar: ../../../../../usr/local/opt: Cannot utime: Permission denied
/opt/homebrew/bin/gtar: Exiting with failure status due to previous errors
Warning: Failed to restore: "/opt/homebrew/bin/gtar" failed with error: The process '/opt/homebrew/bin/gtar' failed with exit code 2
Cache not found for input keys: brew-cache-macOS-0305e7d1fec85c978b1856b2aa2011752ada64d9eecb4ea0b966dca8e14672c8, brew-cache-macOS-

[KaruroChori]

I see, my understanding is that would allow to reuse a good chunk of data needed to setup the build environment, effectively reducing the time taken in CI pipelines.

Sadly I am not really able to assist on that, so if you feel like it is not getting anywhere or it is too easy to break, let's skip it for now and we can always revise the idea once more of the CI is up and running.