Implement dependency specification resolution

[qsantos]

https://github.com/helsing-ai/buffrs/pull/18 brought support for the syntax of dependency specification. However, currently, only pinning (e.g. =X.Y.Z) is actually implemented. Supporting caret version constraints (e.g. ^X.Y.Z) and making the default would increase usability significantly.

Dynamic dependency resolutions looks like a sought-after features among users to allow updating a dependency without having to update all the intermediary packages.

See also PubGrub.

[heatonmatthew]

This would be a useful feature. I'm just getting into Rust, but I might try to find time to look into implementing this. Has there been any design thinking or progress done that I should be aware of as I start to think about it?

[heatonmatthew]

The PubGrub crate is Mozilla Public License 2.0. I presume that wouldn't be a problem with this project's Apache license?

[mara-schulke]

Hi @heatonmatthew, there has not been extensive system design of this beyond some concepts and drafts which indicated that this will require significant internal rewiring of buffrs!:)