Eric N. Vander Weele 7fc51afd59 ci: Use ubuntu-latest for CI on Linux
Ubuntu 18.04 is deprecated on GitHub Actions. Additionally:

- Install 'clang' to get the latest clang toolchain.
    - Use -gdwarf-4 so Valgrind understands the debug information.
- Install latest version of gtest (v1.13.0).
- Show compile and link commands when building.
- `cat` Valgrind output on error.
2023-04-11 15:39:50 -04:00
..
2020-06-05 18:16:07 +08:00
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