[PATCH 0/3] un-breaking osx-gcc ci job

The osx-gcc job seems to break reliably for me, which started in the last week or so (since the last time I actually triggered CI). The third patch fixes it, but I noticed while investigating that the job is not even running gcc at all! That's fixed in the second patch. And the first one is just a cleanup I found along the way.

I'm not sure that this job carries a huge amount of value over the osx-clang one, so we might consider just ditching it. But in the meantime, this should get things passing again.

  [1/3]: ci: drop mention of BREW_INSTALL_PACKAGES variable
  [2/3]: ci: avoid bare "gcc" for osx-gcc job
  [3/3]: ci: stop installing "gcc-13" for osx-gcc

 .github/workflows/main.yml | 3 +--
 ci/install-dependencies.sh | 2 --
 2 files changed, 1 insertion(+), 4 deletions(-)

-Peff