🐛 Mouse scroll not working about delta

[dandavison]

Hi @dougg0k, can you check the existing issues on this topic? E.g.
#630
#58

I don't use mouse-scrolling in less/delta I'm afraid and I don't always find it easy to know how to reproduce the problems people report with it.

Less is a bit outdated here, but since it works the functionality works straight in a file, it also should on delta.

Note that it's possible that delta could be picking up a different version of less, so you could try setting the absolute path to less explicitly in delta's options or an env var.