Update bib style to match updated natbib package

https://ctan.org/tex-archive/macros/latex/contrib/natbib?lang=en

The uos.bst is now missing doi and other subtle improvements. Maybe uos bst does not add anything at all?

added Refactor label

The diff is small and plainbst now has more better features https://www.diffchecker.com/mVpQJA8a

Removed in 5f4567d1

closed