CI is currently running GCC 11.3.0 (which is the latest 11.x release) and Clang "14.0-55" (which is not an upstream release, but fwiw the latest LLVM 14 release was 14.0.6).
(For GCC, it's enough to use the latest non-LTS Ubuntu, but for Clang, it uses their own repository. It may be necessary to use another repository for GCC in some cases.)
Mistakes happen and it's easily done, so no blame intended here! But if CI covered GCC 12, we may well have caught the following early:
CI is currently running GCC 11.3.0 (which is the latest 11.x release) and Clang "14.0-55" (which is not an upstream release, but fwiw the latest LLVM 14 release was 14.0.6).
I think it's desirable to have GCC 12 and Clang 15 covered in CI. OpenSSL's compiler-zoo.yml (https://github.com/openssl/openssl/blob/master/.github/workflows/compiler-zoo.yml) shows how to get newer GCC and Clang on the Ubuntu images used by github actions.
(For GCC, it's enough to use the latest non-LTS Ubuntu, but for Clang, it uses their own repository. It may be necessary to use another repository for GCC in some cases.)