Deprecate `macos-12-xcode-13` image in favor of macOS 14 support
With our current infrastructure, we can only support 3 images at a time. While we want to change this long-term, we also want to be up-to-date in supporting the latest tools. To be able to release macos-14-xcode-15
we therefore need to deprecate macos-12-xcode-13
.