- Update container for Doxygen workflow. Matches Linux workflow, with newer GLIBC version required by newer actions.
- Fixes macOS workflow to install and configure Conan correctly. Still fails on tests, but that does not seem attributable to the workflow.
* Per actions/runner-images#6002, ubuntu-18.04 is being deprecated. If
latest ever fails in the future, we'll need to fix the jobs anyway, so
catch it early.
* Use long option names
* Force clang-format to ubuntu-20.04 because LLVM 10 is not available for 22.04