remove corutine from repo
// We want to use coroutine.hpp from the system's boost headers if possible.
// However, very old Boost versions (provided by RHEL 7 or CentOS 7) didn't have
// this header. So we can resort to our bundled version, but only if necessary.
#ifdef HAVE_BOOST_ASIO_COROUTINE_HPP
#include <boost/asio/coroutine.hpp>
#else
#include <ext/coroutine/coroutine.hpp>
#endif
as neither of the distributions and versions are currently supported, we can remove the ```ext/coroutine/coroutine.hpp``` from the repo and remove the ifdef