RUSTSEC-2020-0130 Bunch<T> unconditionally implements Send/Sync

Affected versions of this crate unconditionally implements Send/Sync for Bunch. This allows users to insert T: !Sync to Bunch. It is possible to create a data race to a T: !Sync by invoking the Bunch::get API which returns &T from multiple threads. It is also possible to send T: !Send to other...