[PATCH] CI: upgrade to macos-12, and pin OSX version

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Per [1] and the warnings our CI is emitting GitHub is phasing in
"macos-12" as their "macos-latest".

As with [2], let's pin our image to a specific version so that we're
not having it swept from under us, and our upgrade cycle can be more
predictable than whenever GitHub changes their images.

1. https://github.com/actions/runner-images/issues/6384
2. 0178420b9ca (github-actions: run gcc-8 on ubuntu-20.04 image,
   2022-11-25)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

This is intended as a sibling to
https://lore.kernel.org/git/xmqq1qpd9bys.fsf@gitster.g/, and along
with another change I'm about to submit should make the CI warning
free.

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

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 9afacfa0b33..1ac11648854 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -238,11 +238,11 @@ jobs:
             pool: ubuntu-20.04
           - jobname: osx-clang
             cc: clang
-            pool: macos-latest
+            pool: macos-12
           - jobname: osx-gcc
             cc: gcc
             cc_package: gcc-9
-            pool: macos-latest
+            pool: macos-12
           - jobname: linux-gcc-default
             cc: gcc
             pool: ubuntu-latest
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index d8fafc8ed2d..4f407530d30 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -30,7 +30,7 @@ ubuntu-*)
 		cp git-lfs-$LINUX_GIT_LFS_VERSION/git-lfs .
 	popd
 	;;
-macos-latest)
+macos-*)
 	export HOMEBREW_NO_AUTO_UPDATE=1 HOMEBREW_NO_INSTALL_CLEANUP=1
 	# Uncomment this if you want to run perf tests:
 	# brew install gnu-time
diff --git a/ci/lib.sh b/ci/lib.sh
index cb30699f34d..706e3ba7e93 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -252,7 +252,7 @@ ubuntu-*)
 	GIT_LFS_PATH="$HOME/custom/git-lfs"
 	export PATH="$GIT_LFS_PATH:$P4_PATH:$PATH"
 	;;
-macos-latest)
+macos-*)
 	if [ "$jobname" = osx-gcc ]
 	then
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=$(which python3)"
-- 
2.39.0.rc2.1017.g5f0c708352f