Update gix to 0.84

[cruessler]

This is a follow-up to #2962.

[extrawurst]

@cruessler what does it take to mark this as out-of-draft?

[cruessler]

@extrawurst ssh-key is still a release candidate at 0.7.0-rc.10. I’m fine with merging as-is, but I wanted to at least have mentioned it. With respect to changes related to gitoxide, there’s nothing left on my to-do list.