Grouping is a nice feature, but it wasn't helpful here. If there's an error in rubocop for example, the rubocop section will be collapsed, and because we didn't close the group, the haml group was always open. So it wasn't clear where the error was.
Better to just show all the output, which isn't very long, so you can see where the problem is straight away.
Even better would be to add support for GitHub Actions annotations. I thought we used to have that turned on, not sure why it's not working now.
We can somewhat easily get it passing and integrate nice with reviewdog
by adding a TODO file for the rules that we had enabled, so that we
don't need to correct anything now, but we still get alerted for new
offenses. So I say let's keep it and enforce it from now on.
So that we can control the version we run without depending on external
actions, and so that we use a consistent version for all linters.
At the same time, unify to running the latest version of reviewdog,
0.21.0, which also involves changing the deprecated `fail_on_error` flag
previously used by prettier action to `fail_level`.
