Update to align with the new (2024/Feb) libnfs API

[cwedgwood]

bump the version to reflect this

bump edition to 2021

[cwedgwood]

@cholcombe973 this is working for me though testing is limited, i'm not sure if this needs further work and it's not clear (to me) if it should go into the main branch

it will fail CI because that is using the older libnfs

[cholcombe973]

I think these changes all look fine. I've only done some light testing as well. We could probably setup an integration test in the GitHub workflow if we wanted that could validate it.

[cwedgwood]

@cholcombe973

OK, there are a few things going on here which I didn't plan on initially.

I'm using the rs- prefix to disambiguate this from libnfs. In general, I'm not a fan of such prefixes but it seems hard to avoid given libnfs is already a thing and it is reasonable to have them both checked out at the same time in the same place. As the crate exists with the old name ... I'm not sure what if anything you want to do here.

To utilize the new updated libnfs I'm cloning it from my repo, it could and probably should come from upstream, but as this was in flux I wanted something I could confirm was working (this can be solved by using ref later).

I need this to rebuild libnfs-sys with the updated libnfs - to make this work I have the dependency of type git - again pointing to my repo for the same reasons as needing it to work and be a known quantity.

I made some minor restructuring to the workflow to accommodate this and perhaps leave for other things later.

[cwedgwood]

@cholcombe973 another small update to use canonical upstream repos and specific (tested) refs.