cbus::Message::new is missing Send bound on callback

Since callback is executed in different thread it must implement Send. Otherwise you can easily cause havoc by passing thread unsafe primitives like Rc.

Code: https://git.picodata.io/picodata/picodata/tarantool-module/-/blob/master/tarantool/src/cbus/mod.rs#L99

cc @k.derevtsov, I'm assigning this to you, but let me know if you need any help with that. Please mention me in MR when you'll make a patch