add rust version to crates

[rnbguy]

Description

Currently, tendermint crates don't have any rust-version set.

The tendemint-proto@0.40.0 has MSRV 1.79.0 for parity-scale-codec@3.7.0.

Definition of "done"

Release of tendermint crates with appropriate rust-version.

cargo-hack and cargo-msrv can be used to find them.

cargo hack msrv find --min 1.60 --all-features

Ref: paritytech/parity-scale-codec#646 (comment)