Added automatic publishing to crates.io on publish

[rdelfin]

The last few releases of the rust crate have not gotten published to crates.io, presumably as they still require publishing manually. This causes a mismatch in CLI and library versions that can introduce breaking changes which are only solvable by pulling in flatbuffer versions directly from github instead of going through crates.io, which is not ideal (see #8257).

This PR adds support for automatically publishing to the rust crates library using katyo/publish-crates github action. This will need adding the appropriate secrets from your side.

Resolves #8257