Ansible v2.21.2: Timeout callback and fact gathering fixes

Ansible v2.21.2 includes a new timeout callback for ansible-test that dumps thread stacks when tests approach their deadline. It also enhances parallel fact gathering by improving how timeouts are handled and fixing a hang caused by corrupt async job files. Additionally, a bugfix addresses bcrypt salt string formatting issues on musl libc. These updates are primarily relevant to users of ansible-test and those employing parallel fact gathering.