Ensured any bot PRs will assign humans to issues

[ESadek-MO]

See SciTools/cf-units#571 for evidence it works.

I couldn't create an issue to test 69dadac, due to the nature of the code, but I beleive the functionality is the same.

[pp-mo]

Tiny change

As discussed, I found this a bit confusing + was going to suggest some changes to hopefully make the code logic clearer.
But, from discussion, that should be left to another time. So maybe I'll propose that after if I can come up with something,