* Replace retired macOS 14 runner and test all available Xcode versions
GitHub retires the macos-14 image on 2026-11-02 (brownouts from
2026-10-05). Xcode 15 is not available on any remaining hosted
runner, so drop the macos-14 job and its documented compilers.
Also test the Xcode versions that the images provide but CI did not
use (26.1.1-26.3 on macos-15, 26.4.1-26.6 on a new macos-26 job), and
pin GCC 16 explicitly next to gcc:latest.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document new Xcode and GCC versions in the supported compilers table
Versions taken from the CI logs of this PR (Xcode 26.1.1-26.6) and
from the gcc:16 image (same digest as gcc:16.2.0 and gcc:latest).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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Signed-off-by: Niels Lohmann <mail@nlohmann.me>