rebar: Update binary to work with Erlang/OTP 24-27

It is compiled from its git repository, main branch,
using erlang:24-slim docker image.

To compile using rebar and Erlang 20.0 up to 23.3,
you can download the old binary from ejabberd 21.12, available at:
  https://github.com/processone/ejabberd/raw/21.12/rebar