The derive feature should be stricter in its dependency specification

[mathstuf]

With -Z minimal-versions becoming a thing and me trying to get it to work for my crates, I've been running into issues. One is that serde's derive feature just requires "1.0". This easily ends up being 1.0.0 in such builds and is generally not supportive of all the attributes usable in newer serde versions. This version specification should be stricter.

I don't know if it'd be easy to test in this crate directly because I suspect the versions are always going to be unified and end up using the serde_derive sitting right beside it instead of some theoretical minimum.

The first step would be to find the oldest version of serde_derive which supports all the features documented in the serde crate and which generates code which works for that version of serde.

Or just punt and require that the versions of serde_derive == serde one way or another.

If this ends up coming to any conclusion about the overall interaction this use case and the proposed feature, we should report it to the cargo tracking issue: rust-lang/cargo#5657