How to change versions when changing a package multiple times in one MR?

This question came up here: https://gitlab.postmarketos.org/postmarketos/pmaports/-/merge_requests/2945#note_867953185

For me the most important part is that the last time a package is changed in the merge request, the version is increased.

I've split this question out into this issue for further discussion, so we can think of a good solution once, document it in the wiki, and then avoid this discussion in the future. I'll also bring this up in the next team meeting, but if somebody has strong opinions, please post them here.