use `shell: bash` in GitHub Actions

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The default shell in GitHub Actions does not include -o pipefail. You need to specify shell: bash for it to be included.

That option will cause commands to fail in any part of a pipeline fails.

See https://gist.github.com/mohanpedala/1e2ff5661761d3abd0385e8223e16425#set--o-pipefail https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#defaultsrunshell

[firewave]

We should also make sure that our scripts also use the stricter behavior. And obviously that should be extended to Cppcheck as well.