Merge branch 'ab/ci-use-macos-12'

CI fix.

* ab/ci-use-macos-12:
  CI: upgrade to macos-12, and pin OSX version

diff --cc .github/workflows/main.yml
index 286319d789a1b4de9d4843ae468566173cda2aa8,3413a2a1d4b50857198389eb3ae9bab36d6841f7..71bf71bbe91c2d180c4a6cfcb8ac32feae384ce4
--- 1/.github/workflows/main.yml
--- 2/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@@ -231,14 -232,15 +231,14 @@@ jobs
            - jobname: linux-gcc
              cc: gcc
              cc_package: gcc-8
 -            pool: ubuntu-latest
 +            pool: ubuntu-20.04
            - jobname: linux-TEST-vars
              cc: gcc
 -            os: ubuntu
              cc_package: gcc-8
 -            pool: ubuntu-latest
 +            pool: ubuntu-20.04
            - jobname: osx-clang
              cc: clang
-             pool: macos-latest
+             pool: macos-12
            - jobname: osx-gcc
              cc: gcc
              cc_package: gcc-9

diff --cc ci/install-dependencies.sh
Simple merge

diff --cc ci/lib.sh
Simple merge