CI: turn on -Werror for MacOS build
The build is error-free and we want to keep it that way.
We'd also like to make Timm do real work instead of having to fix clang warnings all the time and this build is a clang build.
The build is error-free and we want to keep it that way.
We'd also like to make Timm do real work instead of having to fix clang warnings all the time and this build is a clang build.