remove rustc-serialize

[est31]

serde 1.0 has been around since over two years now, so I think one could think about removing rustc-serialize. Of course this is a breaking change so should wait until the next major release. I see you are doing major releases every now and then.

[jqnatividad]

Hi @alkis , any chance rust-serialize will be replaced by serde?

rustc-serialize is now archived and there is even a advisory about it.
https://rustsec.org/advisories/RUSTSEC-2022-0004

[jonathanstrong]

rustc-serialize is an optional dependency, and serde integration is also implemented, though? as far as I understand rustc-serialize is entirely opt-in and does not prevent or impede serde usage.

[est31]

It would make a lot of sense to remove it from the set of default features at least, if removing it entirely is not desired. A lot of people just use this crate without turning off default features, and thus get rustc-serialize without having asked for it.

[biot023]

Just to bump this -- I'm getting a future incompatibility report when running cargo check, now.