Errors from work request render badly, they should wrap

Consider https://debusine.debian.net/debian/developers/work-request/85640/?view=generic:

The error message from work_request.output_data (often a single line) is displayed in a list of <pre><code> tags that grows to infinite width and is unreadable once the scrollbar appears.

We should make this wrap in some way. Or maybe not use <pre> and use some of fancier error reporting styling in Django.