[Pkg-rust-maintainers] Bug#1025690: Bug#1025690: rust-clap-3: please upgrade to v4

[peter green]

reassign 1025690 rust-clap
thanks

> Please upgrade to newer upstream branch v4

normal practice in the rust team when packaging multiple versions is that the
package with no version in it's name is the most recent version packaged, and
packages with versions in their name are used for older versions. Reassigning
accordingly.

> (or v5).

v5 doesn't seem to exist at this time.